diff --git a/CHANGELOG.md b/CHANGELOG.md
index f735d43be18..4a890c6d138 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,23 @@
 # Changelog
 
+## Unreleased
+
+* Add support for ES5-style identifiers ([#1349](https://github.com/evanw/esbuild/issues/1349))
+
+    In ES6 and above, an identifier is a character sequence starting with a character in the `ID_Start` Unicode category and followed by zero or more characters in the `ID_Continue` Unicode category, and these categories must be drawn from Unicode version 5.1 or above.
+
+    But in ES5, an identifier is a character sequence starting with a character in one of the `Lu, Ll, Lt, Lm, Lo, Nl` Unicode categories and followed by zero or more characters in the `Lu, Ll, Lt, Lm, Lo, Nl, Mn, Mc, Nd, Pc` Unicode categories, and these categories must be drawn from Unicode version 3.0.
+
+    Previously esbuild always used the ES6+ identifier validation test but with this release, it will use the ES5 validation test when the target environment doesn't support ES6+ identifiers. This identifier validation test is used in decisions related to code printing. For example:
+
+    ```
+    $ echo x.ꓷꓶꓲꓵꓭꓢꓱ | ./esbuild --charset=utf8
+    x.ꓷꓶꓲꓵꓭꓢꓱ;
+
+    $ echo x.ꓷꓶꓲꓵꓭꓢꓱ | ./esbuild --charset=utf8 --target=es5
+    x["ꓷꓶꓲꓵꓭꓢꓱ"];
+    ```
+
 ## 0.12.6
 
 * Improve template literal lowering transformation conformance ([#1327](https://github.com/evanw/esbuild/issues/1327))
diff --git a/internal/bundler/linker.go b/internal/bundler/linker.go
index bfa71d54ea5..c18a3af9934 100644
--- a/internal/bundler/linker.go
+++ b/internal/bundler/linker.go
@@ -1646,7 +1646,7 @@ func (c *linkerContext) generateCodeForLazyExport(sourceIndex uint32) {
 		clone.Properties = append(make([]js_ast.Property, 0, len(clone.Properties)), clone.Properties...)
 		for i, property := range clone.Properties {
 			if str, ok := property.Key.Data.(*js_ast.EString); ok &&
-				(!file.IsEntryPoint() || js_lexer.IsIdentifierUTF16(str.Value) ||
+				(!file.IsEntryPoint() || js_lexer.IsIdentifierUTF16(str.Value, 0) ||
 					!c.options.UnsupportedJSFeatures.Has(compat.ArbitraryModuleNamespaceNames)) {
 				name := js_lexer.UTF16ToString(str.Value)
 				exportRef := generateExport(name, name, property.ValueOrNil).ref
@@ -4168,7 +4168,7 @@ func (c *linkerContext) renameSymbolsInChunk(chunk *chunkInfo, filesInOrder []ui
 	}
 
 	// When we're not minifying, just append numbers to symbol names to avoid collisions
-	r := renamer.NewNumberRenamer(c.graph.Symbols, reservedNames)
+	r := renamer.NewNumberRenamer(c.graph.Symbols, reservedNames, c.options.UnsupportedJSFeatures)
 	nestedScopes := make(map[uint32][]*js_ast.Scope)
 
 	timer.Begin("Add top-level symbols")
diff --git a/internal/compat/js_table.go b/internal/compat/js_table.go
index 425a8f896ca..f1c80ca1de7 100644
--- a/internal/compat/js_table.go
+++ b/internal/compat/js_table.go
@@ -79,6 +79,7 @@ const (
 	TemplateLiteral
 	TopLevelAwait
 	UnicodeEscapes
+	UpdatedIdentifiers
 )
 
 func (features JSFeature) Has(feature JSFeature) bool {
@@ -417,6 +418,15 @@ var jsTable = map[JSFeature]map[Engine][]int{
 		Node:    {4},
 		Safari:  {9},
 	},
+	UpdatedIdentifiers: {
+		Chrome:  {58},
+		Edge:    {14},
+		ES:      {2015},
+		Firefox: {52},
+		IOS:     {14},
+		Node:    {8},
+		Safari:  {14},
+	},
 }
 
 func isVersionLessThan(a []int, b []int) bool {
diff --git a/internal/js_lexer/js_lexer.go b/internal/js_lexer/js_lexer.go
index fc92e6d83ae..d66dcc8c3cb 100644
--- a/internal/js_lexer/js_lexer.go
+++ b/internal/js_lexer/js_lexer.go
@@ -20,6 +20,7 @@ import (
 	"unicode"
 	"unicode/utf8"
 
+	"github.com/evanw/esbuild/internal/compat"
 	"github.com/evanw/esbuild/internal/js_ast"
 	"github.com/evanw/esbuild/internal/logger"
 )
@@ -559,17 +560,17 @@ func (lexer *Lexer) maybeExpandEquals() {
 	}
 }
 
-func IsIdentifier(text string) bool {
+func IsIdentifier(text string, unsupportedJSFeatures compat.JSFeature) bool {
 	if len(text) == 0 {
 		return false
 	}
 	for i, codePoint := range text {
 		if i == 0 {
-			if !IsIdentifierStart(codePoint) {
+			if !IsIdentifierStart(codePoint, unsupportedJSFeatures) {
 				return false
 			}
 		} else {
-			if !IsIdentifierContinue(codePoint) {
+			if !IsIdentifierContinue(codePoint, unsupportedJSFeatures) {
 				return false
 			}
 		}
@@ -577,8 +578,8 @@ func IsIdentifier(text string) bool {
 	return true
 }
 
-func ForceValidIdentifier(text string) string {
-	if IsIdentifier(text) {
+func ForceValidIdentifier(text string, unsupportedJSFeatures compat.JSFeature) string {
+	if IsIdentifier(text, unsupportedJSFeatures) {
 		return text
 	}
 	sb := strings.Builder{}
@@ -586,7 +587,7 @@ func ForceValidIdentifier(text string) string {
 	// Identifier start
 	c, width := utf8.DecodeRuneInString(text)
 	text = text[width:]
-	if IsIdentifierStart(c) {
+	if IsIdentifierStart(c, unsupportedJSFeatures) {
 		sb.WriteRune(c)
 	} else {
 		sb.WriteRune('_')
@@ -596,7 +597,7 @@ func ForceValidIdentifier(text string) string {
 	for text != "" {
 		c, width := utf8.DecodeRuneInString(text)
 		text = text[width:]
-		if IsIdentifierContinue(c) {
+		if IsIdentifierContinue(c, unsupportedJSFeatures) {
 			sb.WriteRune(c)
 		} else {
 			sb.WriteRune('_')
@@ -607,7 +608,7 @@ func ForceValidIdentifier(text string) string {
 }
 
 // This does "IsIdentifier(UTF16ToString(text))" without any allocations
-func IsIdentifierUTF16(text []uint16) bool {
+func IsIdentifierUTF16(text []uint16, unsupportedJSFeatures compat.JSFeature) bool {
 	n := len(text)
 	if n == 0 {
 		return false
@@ -622,11 +623,11 @@ func IsIdentifierUTF16(text []uint16) bool {
 			}
 		}
 		if isStart {
-			if !IsIdentifierStart(r1) {
+			if !IsIdentifierStart(r1, unsupportedJSFeatures) {
 				return false
 			}
 		} else {
-			if !IsIdentifierContinue(r1) {
+			if !IsIdentifierContinue(r1, unsupportedJSFeatures) {
 				return false
 			}
 		}
@@ -634,7 +635,7 @@ func IsIdentifierUTF16(text []uint16) bool {
 	return true
 }
 
-func IsIdentifierStart(codePoint rune) bool {
+func IsIdentifierStart(codePoint rune, unsupportedJSFeatures compat.JSFeature) bool {
 	switch codePoint {
 	case '_', '$',
 		'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
@@ -649,10 +650,14 @@ func IsIdentifierStart(codePoint rune) bool {
 		return false
 	}
 
-	return unicode.Is(idStart, codePoint)
+	if unsupportedJSFeatures.Has(compat.UpdatedIdentifiers) {
+		return unicode.Is(idStartES5, codePoint)
+	} else {
+		return unicode.Is(idStart, codePoint)
+	}
 }
 
-func IsIdentifierContinue(codePoint rune) bool {
+func IsIdentifierContinue(codePoint rune, unsupportedJSFeatures compat.JSFeature) bool {
 	switch codePoint {
 	case '_', '$', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
 		'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
@@ -672,7 +677,11 @@ func IsIdentifierContinue(codePoint rune) bool {
 		return true
 	}
 
-	return unicode.Is(idContinue, codePoint)
+	if unsupportedJSFeatures.Has(compat.UpdatedIdentifiers) {
+		return unicode.Is(idContinueES5, codePoint)
+	} else {
+		return unicode.Is(idContinue, codePoint)
+	}
 }
 
 // See the "White Space Code Points" table in the ECMAScript standard
@@ -725,7 +734,7 @@ func RangeOfIdentifier(source logger.Source, loc logger.Loc) logger.Range {
 		c, _ = utf8.DecodeRuneInString(text[i:])
 	}
 
-	if IsIdentifierStart(c) || c == '\\' {
+	if IsIdentifierStart(c, 0) || c == '\\' {
 		// Search for the end of the identifier
 		for i < len(text) {
 			c2, width2 := utf8.DecodeRuneInString(text[i:])
@@ -743,7 +752,7 @@ func RangeOfIdentifier(source logger.Source, loc logger.Loc) logger.Range {
 						i++
 					}
 				}
-			} else if !IsIdentifierContinue(c2) {
+			} else if !IsIdentifierContinue(c2, 0) {
 				return logger.Range{Loc: loc, Len: int32(i)}
 			} else {
 				i += width2
@@ -1001,9 +1010,9 @@ func (lexer *Lexer) NextInsideJSXElement() {
 				continue
 			}
 
-			if IsIdentifierStart(lexer.codePoint) {
+			if IsIdentifierStart(lexer.codePoint, 0) {
 				lexer.step()
-				for IsIdentifierContinue(lexer.codePoint) || lexer.codePoint == '-' {
+				for IsIdentifierContinue(lexer.codePoint, 0) || lexer.codePoint == '-' {
 					lexer.step()
 				}
 
@@ -1013,9 +1022,9 @@ func (lexer *Lexer) NextInsideJSXElement() {
 				// can't use this feature to reference JavaScript identifiers.
 				if lexer.codePoint == ':' {
 					lexer.step()
-					if IsIdentifierStart(lexer.codePoint) {
+					if IsIdentifierStart(lexer.codePoint, 0) {
 						lexer.step()
-						for IsIdentifierContinue(lexer.codePoint) || lexer.codePoint == '-' {
+						for IsIdentifierContinue(lexer.codePoint, 0) || lexer.codePoint == '-' {
 							lexer.step()
 						}
 					} else {
@@ -1073,11 +1082,11 @@ func (lexer *Lexer) Next() {
 				if lexer.codePoint == '\\' {
 					lexer.Identifier, _ = lexer.scanIdentifierWithEscapes(privateIdentifier)
 				} else {
-					if !IsIdentifierStart(lexer.codePoint) {
+					if !IsIdentifierStart(lexer.codePoint, 0) {
 						lexer.SyntaxError()
 					}
 					lexer.step()
-					for IsIdentifierContinue(lexer.codePoint) {
+					for IsIdentifierContinue(lexer.codePoint, 0) {
 						lexer.step()
 					}
 					if lexer.codePoint == '\\' {
@@ -1592,7 +1601,7 @@ func (lexer *Lexer) Next() {
 			'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
 			'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z':
 			lexer.step()
-			for IsIdentifierContinue(lexer.codePoint) {
+			for IsIdentifierContinue(lexer.codePoint, 0) {
 				lexer.step()
 			}
 			if lexer.codePoint == '\\' {
@@ -1619,9 +1628,9 @@ func (lexer *Lexer) Next() {
 				continue
 			}
 
-			if IsIdentifierStart(lexer.codePoint) {
+			if IsIdentifierStart(lexer.codePoint, 0) {
 				lexer.step()
-				for IsIdentifierContinue(lexer.codePoint) {
+				for IsIdentifierContinue(lexer.codePoint, 0) {
 					lexer.step()
 				}
 				if lexer.codePoint == '\\' {
@@ -1692,7 +1701,7 @@ func (lexer *Lexer) scanIdentifierWithEscapes(kind identifierKind) (string, T) {
 		}
 
 		// Stop when we reach the end of the identifier
-		if !IsIdentifierContinue(lexer.codePoint) {
+		if !IsIdentifierContinue(lexer.codePoint, 0) {
 			break
 		}
 		lexer.step()
@@ -1711,7 +1720,7 @@ func (lexer *Lexer) scanIdentifierWithEscapes(kind identifierKind) (string, T) {
 	if kind == privateIdentifier {
 		identifier = identifier[1:] // Skip over the "#"
 	}
-	if !IsIdentifier(identifier) {
+	if !IsIdentifier(identifier, 0) {
 		lexer.addRangeError(logger.Range{Loc: logger.Loc{Start: int32(lexer.start)}, Len: int32(lexer.end - lexer.start)},
 			fmt.Sprintf("Invalid identifier: %q", text))
 	}
@@ -2029,7 +2038,7 @@ func (lexer *Lexer) parseNumericLiteralOrDot() {
 	}
 
 	// Identifiers can't occur immediately after numbers
-	if IsIdentifierStart(lexer.codePoint) {
+	if IsIdentifierStart(lexer.codePoint, 0) {
 		lexer.SyntaxError()
 	}
 }
@@ -2058,7 +2067,7 @@ func (lexer *Lexer) ScanRegExp() {
 		case '/':
 			lexer.step()
 			bits := uint32(0)
-			for IsIdentifierContinue(lexer.codePoint) {
+			for IsIdentifierContinue(lexer.codePoint, 0) {
 				switch lexer.codePoint {
 				case 'g', 'i', 'm', 's', 'u', 'y':
 					bit := uint32(1) << uint32(lexer.codePoint-'a')
@@ -2528,7 +2537,7 @@ func hasPrefixWithWordBoundary(text string, prefix string) bool {
 			return true
 		}
 		c, _ := utf8.DecodeRuneInString(text[p:])
-		if !IsIdentifierContinue(c) {
+		if !IsIdentifierContinue(c, 0) {
 			return true
 		}
 	}
diff --git a/internal/js_lexer/unicode.go b/internal/js_lexer/unicode.go
index 3242149afec..49ff38fd64a 100644
--- a/internal/js_lexer/unicode.go
+++ b/internal/js_lexer/unicode.go
@@ -3,6 +3,626 @@ package js_lexer
 
 import "unicode"
 
+var idStartES5 = &unicode.RangeTable{
+	LatinOffset: 117,
+	R16: []unicode.Range16{
+		{Lo: 0x41, Hi: 0x5a, Stride: 1},
+		{Lo: 0x61, Hi: 0x7a, Stride: 1},
+		{Lo: 0xaa, Hi: 0xaa, Stride: 1},
+		{Lo: 0xb5, Hi: 0xb5, Stride: 1},
+		{Lo: 0xba, Hi: 0xba, Stride: 1},
+		{Lo: 0xc0, Hi: 0xd6, Stride: 1},
+		{Lo: 0xd8, Hi: 0xf6, Stride: 1},
+		{Lo: 0xf8, Hi: 0x21f, Stride: 1},
+		{Lo: 0x222, Hi: 0x233, Stride: 1},
+		{Lo: 0x250, Hi: 0x2ad, Stride: 1},
+		{Lo: 0x2b0, Hi: 0x2b8, Stride: 1},
+		{Lo: 0x2bb, Hi: 0x2c1, Stride: 1},
+		{Lo: 0x2d0, Hi: 0x2d1, Stride: 1},
+		{Lo: 0x2e0, Hi: 0x2e4, Stride: 1},
+		{Lo: 0x2ee, Hi: 0x2ee, Stride: 1},
+		{Lo: 0x37a, Hi: 0x37a, Stride: 1},
+		{Lo: 0x386, Hi: 0x386, Stride: 1},
+		{Lo: 0x388, Hi: 0x38a, Stride: 1},
+		{Lo: 0x38c, Hi: 0x38c, Stride: 1},
+		{Lo: 0x38e, Hi: 0x3a1, Stride: 1},
+		{Lo: 0x3a3, Hi: 0x3ce, Stride: 1},
+		{Lo: 0x3d0, Hi: 0x3d7, Stride: 1},
+		{Lo: 0x3da, Hi: 0x3f3, Stride: 1},
+		{Lo: 0x400, Hi: 0x481, Stride: 1},
+		{Lo: 0x48c, Hi: 0x4c4, Stride: 1},
+		{Lo: 0x4c7, Hi: 0x4c8, Stride: 1},
+		{Lo: 0x4cb, Hi: 0x4cc, Stride: 1},
+		{Lo: 0x4d0, Hi: 0x4f5, Stride: 1},
+		{Lo: 0x4f8, Hi: 0x4f9, Stride: 1},
+		{Lo: 0x531, Hi: 0x556, Stride: 1},
+		{Lo: 0x559, Hi: 0x559, Stride: 1},
+		{Lo: 0x561, Hi: 0x587, Stride: 1},
+		{Lo: 0x5d0, Hi: 0x5ea, Stride: 1},
+		{Lo: 0x5f0, Hi: 0x5f2, Stride: 1},
+		{Lo: 0x621, Hi: 0x63a, Stride: 1},
+		{Lo: 0x640, Hi: 0x64a, Stride: 1},
+		{Lo: 0x671, Hi: 0x6d3, Stride: 1},
+		{Lo: 0x6d5, Hi: 0x6d5, Stride: 1},
+		{Lo: 0x6e5, Hi: 0x6e6, Stride: 1},
+		{Lo: 0x6fa, Hi: 0x6fc, Stride: 1},
+		{Lo: 0x710, Hi: 0x710, Stride: 1},
+		{Lo: 0x712, Hi: 0x72c, Stride: 1},
+		{Lo: 0x780, Hi: 0x7a5, Stride: 1},
+		{Lo: 0x905, Hi: 0x939, Stride: 1},
+		{Lo: 0x93d, Hi: 0x93d, Stride: 1},
+		{Lo: 0x950, Hi: 0x950, Stride: 1},
+		{Lo: 0x958, Hi: 0x961, Stride: 1},
+		{Lo: 0x985, Hi: 0x98c, Stride: 1},
+		{Lo: 0x98f, Hi: 0x990, Stride: 1},
+		{Lo: 0x993, Hi: 0x9a8, Stride: 1},
+		{Lo: 0x9aa, Hi: 0x9b0, Stride: 1},
+		{Lo: 0x9b2, Hi: 0x9b2, Stride: 1},
+		{Lo: 0x9b6, Hi: 0x9b9, Stride: 1},
+		{Lo: 0x9dc, Hi: 0x9dd, Stride: 1},
+		{Lo: 0x9df, Hi: 0x9e1, Stride: 1},
+		{Lo: 0x9f0, Hi: 0x9f1, Stride: 1},
+		{Lo: 0xa05, Hi: 0xa0a, Stride: 1},
+		{Lo: 0xa0f, Hi: 0xa10, Stride: 1},
+		{Lo: 0xa13, Hi: 0xa28, Stride: 1},
+		{Lo: 0xa2a, Hi: 0xa30, Stride: 1},
+		{Lo: 0xa32, Hi: 0xa33, Stride: 1},
+		{Lo: 0xa35, Hi: 0xa36, Stride: 1},
+		{Lo: 0xa38, Hi: 0xa39, Stride: 1},
+		{Lo: 0xa59, Hi: 0xa5c, Stride: 1},
+		{Lo: 0xa5e, Hi: 0xa5e, Stride: 1},
+		{Lo: 0xa72, Hi: 0xa74, Stride: 1},
+		{Lo: 0xa85, Hi: 0xa8b, Stride: 1},
+		{Lo: 0xa8d, Hi: 0xa8d, Stride: 1},
+		{Lo: 0xa8f, Hi: 0xa91, Stride: 1},
+		{Lo: 0xa93, Hi: 0xaa8, Stride: 1},
+		{Lo: 0xaaa, Hi: 0xab0, Stride: 1},
+		{Lo: 0xab2, Hi: 0xab3, Stride: 1},
+		{Lo: 0xab5, Hi: 0xab9, Stride: 1},
+		{Lo: 0xabd, Hi: 0xabd, Stride: 1},
+		{Lo: 0xad0, Hi: 0xad0, Stride: 1},
+		{Lo: 0xae0, Hi: 0xae0, Stride: 1},
+		{Lo: 0xb05, Hi: 0xb0c, Stride: 1},
+		{Lo: 0xb0f, Hi: 0xb10, Stride: 1},
+		{Lo: 0xb13, Hi: 0xb28, Stride: 1},
+		{Lo: 0xb2a, Hi: 0xb30, Stride: 1},
+		{Lo: 0xb32, Hi: 0xb33, Stride: 1},
+		{Lo: 0xb36, Hi: 0xb39, Stride: 1},
+		{Lo: 0xb3d, Hi: 0xb3d, Stride: 1},
+		{Lo: 0xb5c, Hi: 0xb5d, Stride: 1},
+		{Lo: 0xb5f, Hi: 0xb61, Stride: 1},
+		{Lo: 0xb85, Hi: 0xb8a, Stride: 1},
+		{Lo: 0xb8e, Hi: 0xb90, Stride: 1},
+		{Lo: 0xb92, Hi: 0xb95, Stride: 1},
+		{Lo: 0xb99, Hi: 0xb9a, Stride: 1},
+		{Lo: 0xb9c, Hi: 0xb9c, Stride: 1},
+		{Lo: 0xb9e, Hi: 0xb9f, Stride: 1},
+		{Lo: 0xba3, Hi: 0xba4, Stride: 1},
+		{Lo: 0xba8, Hi: 0xbaa, Stride: 1},
+		{Lo: 0xbae, Hi: 0xbb5, Stride: 1},
+		{Lo: 0xbb7, Hi: 0xbb9, Stride: 1},
+		{Lo: 0xc05, Hi: 0xc0c, Stride: 1},
+		{Lo: 0xc0e, Hi: 0xc10, Stride: 1},
+		{Lo: 0xc12, Hi: 0xc28, Stride: 1},
+		{Lo: 0xc2a, Hi: 0xc33, Stride: 1},
+		{Lo: 0xc35, Hi: 0xc39, Stride: 1},
+		{Lo: 0xc60, Hi: 0xc61, Stride: 1},
+		{Lo: 0xc85, Hi: 0xc8c, Stride: 1},
+		{Lo: 0xc8e, Hi: 0xc90, Stride: 1},
+		{Lo: 0xc92, Hi: 0xca8, Stride: 1},
+		{Lo: 0xcaa, Hi: 0xcb3, Stride: 1},
+		{Lo: 0xcb5, Hi: 0xcb9, Stride: 1},
+		{Lo: 0xcde, Hi: 0xcde, Stride: 1},
+		{Lo: 0xce0, Hi: 0xce1, Stride: 1},
+		{Lo: 0xd05, Hi: 0xd0c, Stride: 1},
+		{Lo: 0xd0e, Hi: 0xd10, Stride: 1},
+		{Lo: 0xd12, Hi: 0xd28, Stride: 1},
+		{Lo: 0xd2a, Hi: 0xd39, Stride: 1},
+		{Lo: 0xd60, Hi: 0xd61, Stride: 1},
+		{Lo: 0xd85, Hi: 0xd96, Stride: 1},
+		{Lo: 0xd9a, Hi: 0xdb1, Stride: 1},
+		{Lo: 0xdb3, Hi: 0xdbb, Stride: 1},
+		{Lo: 0xdbd, Hi: 0xdbd, Stride: 1},
+		{Lo: 0xdc0, Hi: 0xdc6, Stride: 1},
+		{Lo: 0xe01, Hi: 0xe30, Stride: 1},
+		{Lo: 0xe32, Hi: 0xe33, Stride: 1},
+		{Lo: 0xe40, Hi: 0xe46, Stride: 1},
+		{Lo: 0xe81, Hi: 0xe82, Stride: 1},
+		{Lo: 0xe84, Hi: 0xe84, Stride: 1},
+		{Lo: 0xe87, Hi: 0xe88, Stride: 1},
+		{Lo: 0xe8a, Hi: 0xe8a, Stride: 1},
+		{Lo: 0xe8d, Hi: 0xe8d, Stride: 1},
+		{Lo: 0xe94, Hi: 0xe97, Stride: 1},
+		{Lo: 0xe99, Hi: 0xe9f, Stride: 1},
+		{Lo: 0xea1, Hi: 0xea3, Stride: 1},
+		{Lo: 0xea5, Hi: 0xea5, Stride: 1},
+		{Lo: 0xea7, Hi: 0xea7, Stride: 1},
+		{Lo: 0xeaa, Hi: 0xeab, Stride: 1},
+		{Lo: 0xead, Hi: 0xeb0, Stride: 1},
+		{Lo: 0xeb2, Hi: 0xeb3, Stride: 1},
+		{Lo: 0xebd, Hi: 0xebd, Stride: 1},
+		{Lo: 0xec0, Hi: 0xec4, Stride: 1},
+		{Lo: 0xec6, Hi: 0xec6, Stride: 1},
+		{Lo: 0xedc, Hi: 0xedd, Stride: 1},
+		{Lo: 0xf00, Hi: 0xf00, Stride: 1},
+		{Lo: 0xf40, Hi: 0xf47, Stride: 1},
+		{Lo: 0xf49, Hi: 0xf6a, Stride: 1},
+		{Lo: 0xf88, Hi: 0xf8b, Stride: 1},
+	},
+	R32: []unicode.Range32{
+		{Lo: 0x1000, Hi: 0x1021, Stride: 1},
+		{Lo: 0x1023, Hi: 0x1027, Stride: 1},
+		{Lo: 0x1029, Hi: 0x102a, Stride: 1},
+		{Lo: 0x1050, Hi: 0x1055, Stride: 1},
+		{Lo: 0x10a0, Hi: 0x10c5, Stride: 1},
+		{Lo: 0x10d0, Hi: 0x10f6, Stride: 1},
+		{Lo: 0x1100, Hi: 0x1159, Stride: 1},
+		{Lo: 0x115f, Hi: 0x11a2, Stride: 1},
+		{Lo: 0x11a8, Hi: 0x11f9, Stride: 1},
+		{Lo: 0x1200, Hi: 0x1206, Stride: 1},
+		{Lo: 0x1208, Hi: 0x1246, Stride: 1},
+		{Lo: 0x1248, Hi: 0x1248, Stride: 1},
+		{Lo: 0x124a, Hi: 0x124d, Stride: 1},
+		{Lo: 0x1250, Hi: 0x1256, Stride: 1},
+		{Lo: 0x1258, Hi: 0x1258, Stride: 1},
+		{Lo: 0x125a, Hi: 0x125d, Stride: 1},
+		{Lo: 0x1260, Hi: 0x1286, Stride: 1},
+		{Lo: 0x1288, Hi: 0x1288, Stride: 1},
+		{Lo: 0x128a, Hi: 0x128d, Stride: 1},
+		{Lo: 0x1290, Hi: 0x12ae, Stride: 1},
+		{Lo: 0x12b0, Hi: 0x12b0, Stride: 1},
+		{Lo: 0x12b2, Hi: 0x12b5, Stride: 1},
+		{Lo: 0x12b8, Hi: 0x12be, Stride: 1},
+		{Lo: 0x12c0, Hi: 0x12c0, Stride: 1},
+		{Lo: 0x12c2, Hi: 0x12c5, Stride: 1},
+		{Lo: 0x12c8, Hi: 0x12ce, Stride: 1},
+		{Lo: 0x12d0, Hi: 0x12d6, Stride: 1},
+		{Lo: 0x12d8, Hi: 0x12ee, Stride: 1},
+		{Lo: 0x12f0, Hi: 0x130e, Stride: 1},
+		{Lo: 0x1310, Hi: 0x1310, Stride: 1},
+		{Lo: 0x1312, Hi: 0x1315, Stride: 1},
+		{Lo: 0x1318, Hi: 0x131e, Stride: 1},
+		{Lo: 0x1320, Hi: 0x1346, Stride: 1},
+		{Lo: 0x1348, Hi: 0x135a, Stride: 1},
+		{Lo: 0x13a0, Hi: 0x13f4, Stride: 1},
+		{Lo: 0x1401, Hi: 0x166c, Stride: 1},
+		{Lo: 0x166f, Hi: 0x1676, Stride: 1},
+		{Lo: 0x1681, Hi: 0x169a, Stride: 1},
+		{Lo: 0x16a0, Hi: 0x16ea, Stride: 1},
+		{Lo: 0x1780, Hi: 0x17b3, Stride: 1},
+		{Lo: 0x1820, Hi: 0x1877, Stride: 1},
+		{Lo: 0x1880, Hi: 0x18a8, Stride: 1},
+		{Lo: 0x1e00, Hi: 0x1e9b, Stride: 1},
+		{Lo: 0x1ea0, Hi: 0x1ef9, Stride: 1},
+		{Lo: 0x1f00, Hi: 0x1f15, Stride: 1},
+		{Lo: 0x1f18, Hi: 0x1f1d, Stride: 1},
+		{Lo: 0x1f20, Hi: 0x1f45, Stride: 1},
+		{Lo: 0x1f48, Hi: 0x1f4d, Stride: 1},
+		{Lo: 0x1f50, Hi: 0x1f57, Stride: 1},
+		{Lo: 0x1f59, Hi: 0x1f59, Stride: 1},
+		{Lo: 0x1f5b, Hi: 0x1f5b, Stride: 1},
+		{Lo: 0x1f5d, Hi: 0x1f5d, Stride: 1},
+		{Lo: 0x1f5f, Hi: 0x1f7d, Stride: 1},
+		{Lo: 0x1f80, Hi: 0x1fb4, Stride: 1},
+		{Lo: 0x1fb6, Hi: 0x1fbc, Stride: 1},
+		{Lo: 0x1fbe, Hi: 0x1fbe, Stride: 1},
+		{Lo: 0x1fc2, Hi: 0x1fc4, Stride: 1},
+		{Lo: 0x1fc6, Hi: 0x1fcc, Stride: 1},
+		{Lo: 0x1fd0, Hi: 0x1fd3, Stride: 1},
+		{Lo: 0x1fd6, Hi: 0x1fdb, Stride: 1},
+		{Lo: 0x1fe0, Hi: 0x1fec, Stride: 1},
+		{Lo: 0x1ff2, Hi: 0x1ff4, Stride: 1},
+		{Lo: 0x1ff6, Hi: 0x1ffc, Stride: 1},
+		{Lo: 0x207f, Hi: 0x207f, Stride: 1},
+		{Lo: 0x2102, Hi: 0x2102, Stride: 1},
+		{Lo: 0x2107, Hi: 0x2107, Stride: 1},
+		{Lo: 0x210a, Hi: 0x2113, Stride: 1},
+		{Lo: 0x2115, Hi: 0x2115, Stride: 1},
+		{Lo: 0x2119, Hi: 0x211d, Stride: 1},
+		{Lo: 0x2124, Hi: 0x2124, Stride: 1},
+		{Lo: 0x2126, Hi: 0x2126, Stride: 1},
+		{Lo: 0x2128, Hi: 0x2128, Stride: 1},
+		{Lo: 0x212a, Hi: 0x212d, Stride: 1},
+		{Lo: 0x212f, Hi: 0x2131, Stride: 1},
+		{Lo: 0x2133, Hi: 0x2139, Stride: 1},
+		{Lo: 0x2160, Hi: 0x2183, Stride: 1},
+		{Lo: 0x3005, Hi: 0x3007, Stride: 1},
+		{Lo: 0x3021, Hi: 0x3029, Stride: 1},
+		{Lo: 0x3031, Hi: 0x3035, Stride: 1},
+		{Lo: 0x3038, Hi: 0x303a, Stride: 1},
+		{Lo: 0x3041, Hi: 0x3094, Stride: 1},
+		{Lo: 0x309d, Hi: 0x309e, Stride: 1},
+		{Lo: 0x30a1, Hi: 0x30fa, Stride: 1},
+		{Lo: 0x30fc, Hi: 0x30fe, Stride: 1},
+		{Lo: 0x3105, Hi: 0x312c, Stride: 1},
+		{Lo: 0x3131, Hi: 0x318e, Stride: 1},
+		{Lo: 0x31a0, Hi: 0x31b7, Stride: 1},
+		{Lo: 0x3400, Hi: 0x4db5, Stride: 1},
+		{Lo: 0x4e00, Hi: 0x9fa5, Stride: 1},
+		{Lo: 0xa000, Hi: 0xa48c, Stride: 1},
+		{Lo: 0xac00, Hi: 0xd7a3, Stride: 1},
+		{Lo: 0xf900, Hi: 0xfa2d, Stride: 1},
+		{Lo: 0xfb00, Hi: 0xfb06, Stride: 1},
+		{Lo: 0xfb13, Hi: 0xfb17, Stride: 1},
+		{Lo: 0xfb1d, Hi: 0xfb1d, Stride: 1},
+		{Lo: 0xfb1f, Hi: 0xfb28, Stride: 1},
+		{Lo: 0xfb2a, Hi: 0xfb36, Stride: 1},
+		{Lo: 0xfb38, Hi: 0xfb3c, Stride: 1},
+		{Lo: 0xfb3e, Hi: 0xfb3e, Stride: 1},
+		{Lo: 0xfb40, Hi: 0xfb41, Stride: 1},
+		{Lo: 0xfb43, Hi: 0xfb44, Stride: 1},
+		{Lo: 0xfb46, Hi: 0xfbb1, Stride: 1},
+		{Lo: 0xfbd3, Hi: 0xfd3d, Stride: 1},
+		{Lo: 0xfd50, Hi: 0xfd8f, Stride: 1},
+		{Lo: 0xfd92, Hi: 0xfdc7, Stride: 1},
+		{Lo: 0xfdf0, Hi: 0xfdfb, Stride: 1},
+		{Lo: 0xfe70, Hi: 0xfe72, Stride: 1},
+		{Lo: 0xfe74, Hi: 0xfe74, Stride: 1},
+		{Lo: 0xfe76, Hi: 0xfefc, Stride: 1},
+		{Lo: 0xff21, Hi: 0xff3a, Stride: 1},
+		{Lo: 0xff41, Hi: 0xff5a, Stride: 1},
+		{Lo: 0xff66, Hi: 0xffbe, Stride: 1},
+		{Lo: 0xffc2, Hi: 0xffc7, Stride: 1},
+		{Lo: 0xffca, Hi: 0xffcf, Stride: 1},
+		{Lo: 0xffd2, Hi: 0xffd7, Stride: 1},
+		{Lo: 0xffda, Hi: 0xffdc, Stride: 1},
+	},
+}
+
+var idContinueES5 = &unicode.RangeTable{
+	LatinOffset: 128,
+	R16: []unicode.Range16{
+		{Lo: 0x30, Hi: 0x39, Stride: 1},
+		{Lo: 0x41, Hi: 0x5a, Stride: 1},
+		{Lo: 0x5f, Hi: 0x5f, Stride: 1},
+		{Lo: 0x61, Hi: 0x7a, Stride: 1},
+		{Lo: 0xaa, Hi: 0xaa, Stride: 1},
+		{Lo: 0xb5, Hi: 0xb5, Stride: 1},
+		{Lo: 0xba, Hi: 0xba, Stride: 1},
+		{Lo: 0xc0, Hi: 0xd6, Stride: 1},
+		{Lo: 0xd8, Hi: 0xf6, Stride: 1},
+		{Lo: 0xf8, Hi: 0x21f, Stride: 1},
+		{Lo: 0x222, Hi: 0x233, Stride: 1},
+		{Lo: 0x250, Hi: 0x2ad, Stride: 1},
+		{Lo: 0x2b0, Hi: 0x2b8, Stride: 1},
+		{Lo: 0x2bb, Hi: 0x2c1, Stride: 1},
+		{Lo: 0x2d0, Hi: 0x2d1, Stride: 1},
+		{Lo: 0x2e0, Hi: 0x2e4, Stride: 1},
+		{Lo: 0x2ee, Hi: 0x2ee, Stride: 1},
+		{Lo: 0x300, Hi: 0x34e, Stride: 1},
+		{Lo: 0x360, Hi: 0x362, Stride: 1},
+		{Lo: 0x37a, Hi: 0x37a, Stride: 1},
+		{Lo: 0x386, Hi: 0x386, Stride: 1},
+		{Lo: 0x388, Hi: 0x38a, Stride: 1},
+		{Lo: 0x38c, Hi: 0x38c, Stride: 1},
+		{Lo: 0x38e, Hi: 0x3a1, Stride: 1},
+		{Lo: 0x3a3, Hi: 0x3ce, Stride: 1},
+		{Lo: 0x3d0, Hi: 0x3d7, Stride: 1},
+		{Lo: 0x3da, Hi: 0x3f3, Stride: 1},
+		{Lo: 0x400, Hi: 0x481, Stride: 1},
+		{Lo: 0x483, Hi: 0x486, Stride: 1},
+		{Lo: 0x48c, Hi: 0x4c4, Stride: 1},
+		{Lo: 0x4c7, Hi: 0x4c8, Stride: 1},
+		{Lo: 0x4cb, Hi: 0x4cc, Stride: 1},
+		{Lo: 0x4d0, Hi: 0x4f5, Stride: 1},
+		{Lo: 0x4f8, Hi: 0x4f9, Stride: 1},
+		{Lo: 0x531, Hi: 0x556, Stride: 1},
+		{Lo: 0x559, Hi: 0x559, Stride: 1},
+		{Lo: 0x561, Hi: 0x587, Stride: 1},
+		{Lo: 0x591, Hi: 0x5a1, Stride: 1},
+		{Lo: 0x5a3, Hi: 0x5b9, Stride: 1},
+		{Lo: 0x5bb, Hi: 0x5bd, Stride: 1},
+		{Lo: 0x5bf, Hi: 0x5bf, Stride: 1},
+		{Lo: 0x5c1, Hi: 0x5c2, Stride: 1},
+		{Lo: 0x5c4, Hi: 0x5c4, Stride: 1},
+		{Lo: 0x5d0, Hi: 0x5ea, Stride: 1},
+		{Lo: 0x5f0, Hi: 0x5f2, Stride: 1},
+		{Lo: 0x621, Hi: 0x63a, Stride: 1},
+		{Lo: 0x640, Hi: 0x655, Stride: 1},
+		{Lo: 0x660, Hi: 0x669, Stride: 1},
+		{Lo: 0x670, Hi: 0x6d3, Stride: 1},
+		{Lo: 0x6d5, Hi: 0x6dc, Stride: 1},
+		{Lo: 0x6df, Hi: 0x6e8, Stride: 1},
+		{Lo: 0x6ea, Hi: 0x6ed, Stride: 1},
+		{Lo: 0x6f0, Hi: 0x6fc, Stride: 1},
+		{Lo: 0x710, Hi: 0x72c, Stride: 1},
+		{Lo: 0x730, Hi: 0x74a, Stride: 1},
+		{Lo: 0x780, Hi: 0x7b0, Stride: 1},
+		{Lo: 0x901, Hi: 0x903, Stride: 1},
+		{Lo: 0x905, Hi: 0x939, Stride: 1},
+		{Lo: 0x93c, Hi: 0x94d, Stride: 1},
+		{Lo: 0x950, Hi: 0x954, Stride: 1},
+		{Lo: 0x958, Hi: 0x963, Stride: 1},
+		{Lo: 0x966, Hi: 0x96f, Stride: 1},
+		{Lo: 0x981, Hi: 0x983, Stride: 1},
+		{Lo: 0x985, Hi: 0x98c, Stride: 1},
+		{Lo: 0x98f, Hi: 0x990, Stride: 1},
+		{Lo: 0x993, Hi: 0x9a8, Stride: 1},
+		{Lo: 0x9aa, Hi: 0x9b0, Stride: 1},
+		{Lo: 0x9b2, Hi: 0x9b2, Stride: 1},
+		{Lo: 0x9b6, Hi: 0x9b9, Stride: 1},
+		{Lo: 0x9bc, Hi: 0x9bc, Stride: 1},
+		{Lo: 0x9be, Hi: 0x9c4, Stride: 1},
+		{Lo: 0x9c7, Hi: 0x9c8, Stride: 1},
+		{Lo: 0x9cb, Hi: 0x9cd, Stride: 1},
+		{Lo: 0x9d7, Hi: 0x9d7, Stride: 1},
+		{Lo: 0x9dc, Hi: 0x9dd, Stride: 1},
+		{Lo: 0x9df, Hi: 0x9e3, Stride: 1},
+		{Lo: 0x9e6, Hi: 0x9f1, Stride: 1},
+		{Lo: 0xa02, Hi: 0xa02, Stride: 1},
+		{Lo: 0xa05, Hi: 0xa0a, Stride: 1},
+		{Lo: 0xa0f, Hi: 0xa10, Stride: 1},
+		{Lo: 0xa13, Hi: 0xa28, Stride: 1},
+		{Lo: 0xa2a, Hi: 0xa30, Stride: 1},
+		{Lo: 0xa32, Hi: 0xa33, Stride: 1},
+		{Lo: 0xa35, Hi: 0xa36, Stride: 1},
+		{Lo: 0xa38, Hi: 0xa39, Stride: 1},
+		{Lo: 0xa3c, Hi: 0xa3c, Stride: 1},
+		{Lo: 0xa3e, Hi: 0xa42, Stride: 1},
+		{Lo: 0xa47, Hi: 0xa48, Stride: 1},
+		{Lo: 0xa4b, Hi: 0xa4d, Stride: 1},
+		{Lo: 0xa59, Hi: 0xa5c, Stride: 1},
+		{Lo: 0xa5e, Hi: 0xa5e, Stride: 1},
+		{Lo: 0xa66, Hi: 0xa74, Stride: 1},
+		{Lo: 0xa81, Hi: 0xa83, Stride: 1},
+		{Lo: 0xa85, Hi: 0xa8b, Stride: 1},
+		{Lo: 0xa8d, Hi: 0xa8d, Stride: 1},
+		{Lo: 0xa8f, Hi: 0xa91, Stride: 1},
+		{Lo: 0xa93, Hi: 0xaa8, Stride: 1},
+		{Lo: 0xaaa, Hi: 0xab0, Stride: 1},
+		{Lo: 0xab2, Hi: 0xab3, Stride: 1},
+		{Lo: 0xab5, Hi: 0xab9, Stride: 1},
+		{Lo: 0xabc, Hi: 0xac5, Stride: 1},
+		{Lo: 0xac7, Hi: 0xac9, Stride: 1},
+		{Lo: 0xacb, Hi: 0xacd, Stride: 1},
+		{Lo: 0xad0, Hi: 0xad0, Stride: 1},
+		{Lo: 0xae0, Hi: 0xae0, Stride: 1},
+		{Lo: 0xae6, Hi: 0xaef, Stride: 1},
+		{Lo: 0xb01, Hi: 0xb03, Stride: 1},
+		{Lo: 0xb05, Hi: 0xb0c, Stride: 1},
+		{Lo: 0xb0f, Hi: 0xb10, Stride: 1},
+		{Lo: 0xb13, Hi: 0xb28, Stride: 1},
+		{Lo: 0xb2a, Hi: 0xb30, Stride: 1},
+		{Lo: 0xb32, Hi: 0xb33, Stride: 1},
+		{Lo: 0xb36, Hi: 0xb39, Stride: 1},
+		{Lo: 0xb3c, Hi: 0xb43, Stride: 1},
+		{Lo: 0xb47, Hi: 0xb48, Stride: 1},
+		{Lo: 0xb4b, Hi: 0xb4d, Stride: 1},
+		{Lo: 0xb56, Hi: 0xb57, Stride: 1},
+		{Lo: 0xb5c, Hi: 0xb5d, Stride: 1},
+		{Lo: 0xb5f, Hi: 0xb61, Stride: 1},
+		{Lo: 0xb66, Hi: 0xb6f, Stride: 1},
+		{Lo: 0xb82, Hi: 0xb83, Stride: 1},
+		{Lo: 0xb85, Hi: 0xb8a, Stride: 1},
+		{Lo: 0xb8e, Hi: 0xb90, Stride: 1},
+		{Lo: 0xb92, Hi: 0xb95, Stride: 1},
+		{Lo: 0xb99, Hi: 0xb9a, Stride: 1},
+		{Lo: 0xb9c, Hi: 0xb9c, Stride: 1},
+		{Lo: 0xb9e, Hi: 0xb9f, Stride: 1},
+		{Lo: 0xba3, Hi: 0xba4, Stride: 1},
+		{Lo: 0xba8, Hi: 0xbaa, Stride: 1},
+		{Lo: 0xbae, Hi: 0xbb5, Stride: 1},
+		{Lo: 0xbb7, Hi: 0xbb9, Stride: 1},
+		{Lo: 0xbbe, Hi: 0xbc2, Stride: 1},
+		{Lo: 0xbc6, Hi: 0xbc8, Stride: 1},
+		{Lo: 0xbca, Hi: 0xbcd, Stride: 1},
+		{Lo: 0xbd7, Hi: 0xbd7, Stride: 1},
+		{Lo: 0xbe7, Hi: 0xbef, Stride: 1},
+		{Lo: 0xc01, Hi: 0xc03, Stride: 1},
+		{Lo: 0xc05, Hi: 0xc0c, Stride: 1},
+		{Lo: 0xc0e, Hi: 0xc10, Stride: 1},
+		{Lo: 0xc12, Hi: 0xc28, Stride: 1},
+		{Lo: 0xc2a, Hi: 0xc33, Stride: 1},
+		{Lo: 0xc35, Hi: 0xc39, Stride: 1},
+		{Lo: 0xc3e, Hi: 0xc44, Stride: 1},
+		{Lo: 0xc46, Hi: 0xc48, Stride: 1},
+		{Lo: 0xc4a, Hi: 0xc4d, Stride: 1},
+		{Lo: 0xc55, Hi: 0xc56, Stride: 1},
+		{Lo: 0xc60, Hi: 0xc61, Stride: 1},
+		{Lo: 0xc66, Hi: 0xc6f, Stride: 1},
+		{Lo: 0xc82, Hi: 0xc83, Stride: 1},
+		{Lo: 0xc85, Hi: 0xc8c, Stride: 1},
+		{Lo: 0xc8e, Hi: 0xc90, Stride: 1},
+		{Lo: 0xc92, Hi: 0xca8, Stride: 1},
+		{Lo: 0xcaa, Hi: 0xcb3, Stride: 1},
+		{Lo: 0xcb5, Hi: 0xcb9, Stride: 1},
+		{Lo: 0xcbe, Hi: 0xcc4, Stride: 1},
+		{Lo: 0xcc6, Hi: 0xcc8, Stride: 1},
+		{Lo: 0xcca, Hi: 0xccd, Stride: 1},
+		{Lo: 0xcd5, Hi: 0xcd6, Stride: 1},
+		{Lo: 0xcde, Hi: 0xcde, Stride: 1},
+		{Lo: 0xce0, Hi: 0xce1, Stride: 1},
+		{Lo: 0xce6, Hi: 0xcef, Stride: 1},
+		{Lo: 0xd02, Hi: 0xd03, Stride: 1},
+		{Lo: 0xd05, Hi: 0xd0c, Stride: 1},
+		{Lo: 0xd0e, Hi: 0xd10, Stride: 1},
+		{Lo: 0xd12, Hi: 0xd28, Stride: 1},
+		{Lo: 0xd2a, Hi: 0xd39, Stride: 1},
+		{Lo: 0xd3e, Hi: 0xd43, Stride: 1},
+		{Lo: 0xd46, Hi: 0xd48, Stride: 1},
+		{Lo: 0xd4a, Hi: 0xd4d, Stride: 1},
+		{Lo: 0xd57, Hi: 0xd57, Stride: 1},
+		{Lo: 0xd60, Hi: 0xd61, Stride: 1},
+		{Lo: 0xd66, Hi: 0xd6f, Stride: 1},
+		{Lo: 0xd82, Hi: 0xd83, Stride: 1},
+		{Lo: 0xd85, Hi: 0xd96, Stride: 1},
+		{Lo: 0xd9a, Hi: 0xdb1, Stride: 1},
+		{Lo: 0xdb3, Hi: 0xdbb, Stride: 1},
+		{Lo: 0xdbd, Hi: 0xdbd, Stride: 1},
+		{Lo: 0xdc0, Hi: 0xdc6, Stride: 1},
+		{Lo: 0xdca, Hi: 0xdca, Stride: 1},
+		{Lo: 0xdcf, Hi: 0xdd4, Stride: 1},
+		{Lo: 0xdd6, Hi: 0xdd6, Stride: 1},
+		{Lo: 0xdd8, Hi: 0xddf, Stride: 1},
+		{Lo: 0xdf2, Hi: 0xdf3, Stride: 1},
+		{Lo: 0xe01, Hi: 0xe3a, Stride: 1},
+		{Lo: 0xe40, Hi: 0xe4e, Stride: 1},
+		{Lo: 0xe50, Hi: 0xe59, Stride: 1},
+		{Lo: 0xe81, Hi: 0xe82, Stride: 1},
+		{Lo: 0xe84, Hi: 0xe84, Stride: 1},
+		{Lo: 0xe87, Hi: 0xe88, Stride: 1},
+		{Lo: 0xe8a, Hi: 0xe8a, Stride: 1},
+		{Lo: 0xe8d, Hi: 0xe8d, Stride: 1},
+		{Lo: 0xe94, Hi: 0xe97, Stride: 1},
+		{Lo: 0xe99, Hi: 0xe9f, Stride: 1},
+		{Lo: 0xea1, Hi: 0xea3, Stride: 1},
+		{Lo: 0xea5, Hi: 0xea5, Stride: 1},
+		{Lo: 0xea7, Hi: 0xea7, Stride: 1},
+		{Lo: 0xeaa, Hi: 0xeab, Stride: 1},
+		{Lo: 0xead, Hi: 0xeb9, Stride: 1},
+		{Lo: 0xebb, Hi: 0xebd, Stride: 1},
+		{Lo: 0xec0, Hi: 0xec4, Stride: 1},
+		{Lo: 0xec6, Hi: 0xec6, Stride: 1},
+		{Lo: 0xec8, Hi: 0xecd, Stride: 1},
+		{Lo: 0xed0, Hi: 0xed9, Stride: 1},
+		{Lo: 0xedc, Hi: 0xedd, Stride: 1},
+		{Lo: 0xf00, Hi: 0xf00, Stride: 1},
+		{Lo: 0xf18, Hi: 0xf19, Stride: 1},
+		{Lo: 0xf20, Hi: 0xf29, Stride: 1},
+		{Lo: 0xf35, Hi: 0xf35, Stride: 1},
+		{Lo: 0xf37, Hi: 0xf37, Stride: 1},
+		{Lo: 0xf39, Hi: 0xf39, Stride: 1},
+		{Lo: 0xf3e, Hi: 0xf47, Stride: 1},
+		{Lo: 0xf49, Hi: 0xf6a, Stride: 1},
+		{Lo: 0xf71, Hi: 0xf84, Stride: 1},
+		{Lo: 0xf86, Hi: 0xf8b, Stride: 1},
+		{Lo: 0xf90, Hi: 0xf97, Stride: 1},
+		{Lo: 0xf99, Hi: 0xfbc, Stride: 1},
+		{Lo: 0xfc6, Hi: 0xfc6, Stride: 1},
+	},
+	R32: []unicode.Range32{
+		{Lo: 0x1000, Hi: 0x1021, Stride: 1},
+		{Lo: 0x1023, Hi: 0x1027, Stride: 1},
+		{Lo: 0x1029, Hi: 0x102a, Stride: 1},
+		{Lo: 0x102c, Hi: 0x1032, Stride: 1},
+		{Lo: 0x1036, Hi: 0x1039, Stride: 1},
+		{Lo: 0x1040, Hi: 0x1049, Stride: 1},
+		{Lo: 0x1050, Hi: 0x1059, Stride: 1},
+		{Lo: 0x10a0, Hi: 0x10c5, Stride: 1},
+		{Lo: 0x10d0, Hi: 0x10f6, Stride: 1},
+		{Lo: 0x1100, Hi: 0x1159, Stride: 1},
+		{Lo: 0x115f, Hi: 0x11a2, Stride: 1},
+		{Lo: 0x11a8, Hi: 0x11f9, Stride: 1},
+		{Lo: 0x1200, Hi: 0x1206, Stride: 1},
+		{Lo: 0x1208, Hi: 0x1246, Stride: 1},
+		{Lo: 0x1248, Hi: 0x1248, Stride: 1},
+		{Lo: 0x124a, Hi: 0x124d, Stride: 1},
+		{Lo: 0x1250, Hi: 0x1256, Stride: 1},
+		{Lo: 0x1258, Hi: 0x1258, Stride: 1},
+		{Lo: 0x125a, Hi: 0x125d, Stride: 1},
+		{Lo: 0x1260, Hi: 0x1286, Stride: 1},
+		{Lo: 0x1288, Hi: 0x1288, Stride: 1},
+		{Lo: 0x128a, Hi: 0x128d, Stride: 1},
+		{Lo: 0x1290, Hi: 0x12ae, Stride: 1},
+		{Lo: 0x12b0, Hi: 0x12b0, Stride: 1},
+		{Lo: 0x12b2, Hi: 0x12b5, Stride: 1},
+		{Lo: 0x12b8, Hi: 0x12be, Stride: 1},
+		{Lo: 0x12c0, Hi: 0x12c0, Stride: 1},
+		{Lo: 0x12c2, Hi: 0x12c5, Stride: 1},
+		{Lo: 0x12c8, Hi: 0x12ce, Stride: 1},
+		{Lo: 0x12d0, Hi: 0x12d6, Stride: 1},
+		{Lo: 0x12d8, Hi: 0x12ee, Stride: 1},
+		{Lo: 0x12f0, Hi: 0x130e, Stride: 1},
+		{Lo: 0x1310, Hi: 0x1310, Stride: 1},
+		{Lo: 0x1312, Hi: 0x1315, Stride: 1},
+		{Lo: 0x1318, Hi: 0x131e, Stride: 1},
+		{Lo: 0x1320, Hi: 0x1346, Stride: 1},
+		{Lo: 0x1348, Hi: 0x135a, Stride: 1},
+		{Lo: 0x1369, Hi: 0x1371, Stride: 1},
+		{Lo: 0x13a0, Hi: 0x13f4, Stride: 1},
+		{Lo: 0x1401, Hi: 0x166c, Stride: 1},
+		{Lo: 0x166f, Hi: 0x1676, Stride: 1},
+		{Lo: 0x1681, Hi: 0x169a, Stride: 1},
+		{Lo: 0x16a0, Hi: 0x16ea, Stride: 1},
+		{Lo: 0x1780, Hi: 0x17d3, Stride: 1},
+		{Lo: 0x17e0, Hi: 0x17e9, Stride: 1},
+		{Lo: 0x1810, Hi: 0x1819, Stride: 1},
+		{Lo: 0x1820, Hi: 0x1877, Stride: 1},
+		{Lo: 0x1880, Hi: 0x18a9, Stride: 1},
+		{Lo: 0x1e00, Hi: 0x1e9b, Stride: 1},
+		{Lo: 0x1ea0, Hi: 0x1ef9, Stride: 1},
+		{Lo: 0x1f00, Hi: 0x1f15, Stride: 1},
+		{Lo: 0x1f18, Hi: 0x1f1d, Stride: 1},
+		{Lo: 0x1f20, Hi: 0x1f45, Stride: 1},
+		{Lo: 0x1f48, Hi: 0x1f4d, Stride: 1},
+		{Lo: 0x1f50, Hi: 0x1f57, Stride: 1},
+		{Lo: 0x1f59, Hi: 0x1f59, Stride: 1},
+		{Lo: 0x1f5b, Hi: 0x1f5b, Stride: 1},
+		{Lo: 0x1f5d, Hi: 0x1f5d, Stride: 1},
+		{Lo: 0x1f5f, Hi: 0x1f7d, Stride: 1},
+		{Lo: 0x1f80, Hi: 0x1fb4, Stride: 1},
+		{Lo: 0x1fb6, Hi: 0x1fbc, Stride: 1},
+		{Lo: 0x1fbe, Hi: 0x1fbe, Stride: 1},
+		{Lo: 0x1fc2, Hi: 0x1fc4, Stride: 1},
+		{Lo: 0x1fc6, Hi: 0x1fcc, Stride: 1},
+		{Lo: 0x1fd0, Hi: 0x1fd3, Stride: 1},
+		{Lo: 0x1fd6, Hi: 0x1fdb, Stride: 1},
+		{Lo: 0x1fe0, Hi: 0x1fec, Stride: 1},
+		{Lo: 0x1ff2, Hi: 0x1ff4, Stride: 1},
+		{Lo: 0x1ff6, Hi: 0x1ffc, Stride: 1},
+		{Lo: 0x203f, Hi: 0x2040, Stride: 1},
+		{Lo: 0x207f, Hi: 0x207f, Stride: 1},
+		{Lo: 0x20d0, Hi: 0x20dc, Stride: 1},
+		{Lo: 0x20e1, Hi: 0x20e1, Stride: 1},
+		{Lo: 0x2102, Hi: 0x2102, Stride: 1},
+		{Lo: 0x2107, Hi: 0x2107, Stride: 1},
+		{Lo: 0x210a, Hi: 0x2113, Stride: 1},
+		{Lo: 0x2115, Hi: 0x2115, Stride: 1},
+		{Lo: 0x2119, Hi: 0x211d, Stride: 1},
+		{Lo: 0x2124, Hi: 0x2124, Stride: 1},
+		{Lo: 0x2126, Hi: 0x2126, Stride: 1},
+		{Lo: 0x2128, Hi: 0x2128, Stride: 1},
+		{Lo: 0x212a, Hi: 0x212d, Stride: 1},
+		{Lo: 0x212f, Hi: 0x2131, Stride: 1},
+		{Lo: 0x2133, Hi: 0x2139, Stride: 1},
+		{Lo: 0x2160, Hi: 0x2183, Stride: 1},
+		{Lo: 0x3005, Hi: 0x3007, Stride: 1},
+		{Lo: 0x3021, Hi: 0x302f, Stride: 1},
+		{Lo: 0x3031, Hi: 0x3035, Stride: 1},
+		{Lo: 0x3038, Hi: 0x303a, Stride: 1},
+		{Lo: 0x3041, Hi: 0x3094, Stride: 1},
+		{Lo: 0x3099, Hi: 0x309a, Stride: 1},
+		{Lo: 0x309d, Hi: 0x309e, Stride: 1},
+		{Lo: 0x30a1, Hi: 0x30fe, Stride: 1},
+		{Lo: 0x3105, Hi: 0x312c, Stride: 1},
+		{Lo: 0x3131, Hi: 0x318e, Stride: 1},
+		{Lo: 0x31a0, Hi: 0x31b7, Stride: 1},
+		{Lo: 0x3400, Hi: 0x4db5, Stride: 1},
+		{Lo: 0x4e00, Hi: 0x9fa5, Stride: 1},
+		{Lo: 0xa000, Hi: 0xa48c, Stride: 1},
+		{Lo: 0xac00, Hi: 0xd7a3, Stride: 1},
+		{Lo: 0xf900, Hi: 0xfa2d, Stride: 1},
+		{Lo: 0xfb00, Hi: 0xfb06, Stride: 1},
+		{Lo: 0xfb13, Hi: 0xfb17, Stride: 1},
+		{Lo: 0xfb1d, Hi: 0xfb28, Stride: 1},
+		{Lo: 0xfb2a, Hi: 0xfb36, Stride: 1},
+		{Lo: 0xfb38, Hi: 0xfb3c, Stride: 1},
+		{Lo: 0xfb3e, Hi: 0xfb3e, Stride: 1},
+		{Lo: 0xfb40, Hi: 0xfb41, Stride: 1},
+		{Lo: 0xfb43, Hi: 0xfb44, Stride: 1},
+		{Lo: 0xfb46, Hi: 0xfbb1, Stride: 1},
+		{Lo: 0xfbd3, Hi: 0xfd3d, Stride: 1},
+		{Lo: 0xfd50, Hi: 0xfd8f, Stride: 1},
+		{Lo: 0xfd92, Hi: 0xfdc7, Stride: 1},
+		{Lo: 0xfdf0, Hi: 0xfdfb, Stride: 1},
+		{Lo: 0xfe20, Hi: 0xfe23, Stride: 1},
+		{Lo: 0xfe33, Hi: 0xfe34, Stride: 1},
+		{Lo: 0xfe4d, Hi: 0xfe4f, Stride: 1},
+		{Lo: 0xfe70, Hi: 0xfe72, Stride: 1},
+		{Lo: 0xfe74, Hi: 0xfe74, Stride: 1},
+		{Lo: 0xfe76, Hi: 0xfefc, Stride: 1},
+		{Lo: 0xff10, Hi: 0xff19, Stride: 1},
+		{Lo: 0xff21, Hi: 0xff3a, Stride: 1},
+		{Lo: 0xff3f, Hi: 0xff3f, Stride: 1},
+		{Lo: 0xff41, Hi: 0xff5a, Stride: 1},
+		{Lo: 0xff65, Hi: 0xffbe, Stride: 1},
+		{Lo: 0xffc2, Hi: 0xffc7, Stride: 1},
+		{Lo: 0xffca, Hi: 0xffcf, Stride: 1},
+		{Lo: 0xffd2, Hi: 0xffd7, Stride: 1},
+		{Lo: 0xffda, Hi: 0xffdc, Stride: 1},
+	},
+}
+
 var idStart = &unicode.RangeTable{
 	LatinOffset: 117,
 	R16: []unicode.Range16{
diff --git a/internal/js_parser/js_parser.go b/internal/js_parser/js_parser.go
index 0b00a4abf44..4c9319c24c5 100644
--- a/internal/js_parser/js_parser.go
+++ b/internal/js_parser/js_parser.go
@@ -33,44 +33,44 @@ import (
 // to have at least two separate passes to handle variable hoisting. See the
 // comment about scopesInOrder below for more information.
 type parser struct {
-	options                  Options
-	log                      logger.Log
-	source                   logger.Source
-	tracker                  logger.LineColumnTracker
-	lexer                    js_lexer.Lexer
-	allowIn                  bool
-	allowPrivateIdentifiers  bool
-	hasTopLevelReturn        bool
-	latestReturnHadSemicolon bool
-	hasImportMeta            bool
-	hasESModuleSyntax        bool
-	warnedThisIsUndefined    bool
-	topLevelAwaitKeyword     logger.Range
-	fnOrArrowDataParse       fnOrArrowDataParse
-	fnOrArrowDataVisit       fnOrArrowDataVisit
-	fnOnlyDataVisit          fnOnlyDataVisit
-	allocatedNames           []string
-	latestArrowArgLoc        logger.Loc
-	forbidSuffixAfterAsLoc   logger.Loc
-	currentScope             *js_ast.Scope
-	scopesForCurrentPart     []*js_ast.Scope
-	symbols                  []js_ast.Symbol
-	tsUseCounts              []uint32
-	exportsRef               js_ast.Ref
-	requireRef               js_ast.Ref
-	moduleRef                js_ast.Ref
-	importMetaRef            js_ast.Ref
-	promiseRef               js_ast.Ref
-	findSymbolHelper         func(loc logger.Loc, name string) js_ast.Ref
-	symbolForDefineHelper    func(int) js_ast.Ref
-	injectedDefineSymbols    []js_ast.Ref
-	injectedSymbolSources    map[js_ast.Ref]injectedSymbolSource
-	symbolUses               map[js_ast.Ref]js_ast.SymbolUse
-	declaredSymbols          []js_ast.DeclaredSymbol
-	runtimeImports           map[string]js_ast.Ref
-	duplicateCaseChecker     duplicateCaseChecker
-	nonBMPIdentifiers        map[string]bool
-	legacyOctalLiterals      map[js_ast.E]logger.Range
+	options                    Options
+	log                        logger.Log
+	source                     logger.Source
+	tracker                    logger.LineColumnTracker
+	lexer                      js_lexer.Lexer
+	allowIn                    bool
+	allowPrivateIdentifiers    bool
+	hasTopLevelReturn          bool
+	latestReturnHadSemicolon   bool
+	hasImportMeta              bool
+	hasESModuleSyntax          bool
+	warnedThisIsUndefined      bool
+	topLevelAwaitKeyword       logger.Range
+	fnOrArrowDataParse         fnOrArrowDataParse
+	fnOrArrowDataVisit         fnOrArrowDataVisit
+	fnOnlyDataVisit            fnOnlyDataVisit
+	allocatedNames             []string
+	latestArrowArgLoc          logger.Loc
+	forbidSuffixAfterAsLoc     logger.Loc
+	currentScope               *js_ast.Scope
+	scopesForCurrentPart       []*js_ast.Scope
+	symbols                    []js_ast.Symbol
+	tsUseCounts                []uint32
+	exportsRef                 js_ast.Ref
+	requireRef                 js_ast.Ref
+	moduleRef                  js_ast.Ref
+	importMetaRef              js_ast.Ref
+	promiseRef                 js_ast.Ref
+	findSymbolHelper           func(loc logger.Loc, name string) js_ast.Ref
+	symbolForDefineHelper      func(int) js_ast.Ref
+	injectedDefineSymbols      []js_ast.Ref
+	injectedSymbolSources      map[js_ast.Ref]injectedSymbolSource
+	symbolUses                 map[js_ast.Ref]js_ast.SymbolUse
+	declaredSymbols            []js_ast.DeclaredSymbol
+	runtimeImports             map[string]js_ast.Ref
+	duplicateCaseChecker       duplicateCaseChecker
+	unrepresentableIdentifiers map[string]bool
+	legacyOctalLiterals        map[js_ast.E]logger.Range
 
 	// For strict mode handling
 	hoistedRefForSloppyModeBlockFn map[js_ast.Ref]js_ast.Ref
@@ -1381,7 +1381,7 @@ func (p *parser) canMergeSymbols(scope *js_ast.Scope, existing js_ast.SymbolKind
 }
 
 func (p *parser) declareSymbol(kind js_ast.SymbolKind, loc logger.Loc, name string) js_ast.Ref {
-	p.checkForNonBMPCodePoint(loc, name)
+	p.checkForUnrepresentableIdentifier(loc, name)
 
 	// Allocate a new symbol
 	ref := p.newSymbol(kind, name)
@@ -4636,7 +4636,7 @@ func (p *parser) parseClauseAlias(kind string) string {
 	}
 
 	alias := p.lexer.Identifier
-	p.checkForNonBMPCodePoint(loc, alias)
+	p.checkForUnrepresentableIdentifier(loc, alias)
 	return alias
 }
 
@@ -6341,7 +6341,7 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			for i, item := range *stmt.Items {
 				name := p.loadNameFromRef(item.Name.Ref)
 				ref := p.declareSymbol(js_ast.SymbolImport, item.Name.Loc, name)
-				p.checkForNonBMPCodePoint(item.AliasLoc, item.Alias)
+				p.checkForUnrepresentableIdentifier(item.AliasLoc, item.Alias)
 				p.isImportItem[ref] = true
 				(*stmt.Items)[i].Name.Ref = ref
 				itemRefs[item.Alias] = js_ast.LocRef{Loc: item.Name.Loc, Ref: ref}
@@ -6785,7 +6785,7 @@ func (p *parser) findSymbol(loc logger.Loc, name string) findSymbolResult {
 		s = s.Parent
 		if s == nil {
 			// Allocate an "unbound" symbol
-			p.checkForNonBMPCodePoint(loc, name)
+			p.checkForUnrepresentableIdentifier(loc, name)
 			ref = p.newSymbol(js_ast.SymbolUnbound, name)
 			declareLoc = loc
 			p.moduleScope.Members[name] = js_ast.ScopeMember{Ref: ref, Loc: logger.Loc{Start: -1}}
@@ -9107,7 +9107,7 @@ func (p *parser) visitAndAppendStmt(stmts []js_ast.Stmt, stmt js_ast.Stmt) []js_
 				value.ValueOrNil = js_ast.Expr{Loc: value.Loc, Data: js_ast.EUndefinedShared}
 			}
 
-			if p.options.mangleSyntax && js_lexer.IsIdentifier(name) {
+			if p.options.mangleSyntax && js_lexer.IsIdentifier(name, 0) {
 				// "Enum.Name = value"
 				assignTarget = js_ast.Assign(
 					js_ast.Expr{Loc: value.Loc, Data: &js_ast.EDot{
@@ -9561,7 +9561,7 @@ func (p *parser) visitClass(nameScopeLoc logger.Loc, class *js_ast.Class) js_ast
 
 			// "class {['x'] = y}" => "class {x = y}"
 			if p.options.mangleSyntax && property.IsComputed {
-				if str, ok := key.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value) {
+				if str, ok := key.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value, 0) {
 					isInvalidConstructor := false
 					if js_lexer.UTF16EqualsString(str.Value, "constructor") {
 						if !property.IsMethod {
@@ -9821,17 +9821,29 @@ func (p *parser) jsxStringsToMemberExpression(loc logger.Loc, parts []string) js
 	return value
 }
 
-func (p *parser) checkForNonBMPCodePoint(loc logger.Loc, name string) {
+func (p *parser) checkForUnrepresentableIdentifier(loc logger.Loc, name string) {
 	if p.options.asciiOnly && p.options.unsupportedJSFeatures.Has(compat.UnicodeEscapes) &&
 		js_lexer.ContainsNonBMPCodePoint(name) {
-		if p.nonBMPIdentifiers == nil {
-			p.nonBMPIdentifiers = make(map[string]bool)
+		if p.unrepresentableIdentifiers == nil {
+			p.unrepresentableIdentifiers = make(map[string]bool)
 		}
-		if !p.nonBMPIdentifiers[name] {
-			p.nonBMPIdentifiers[name] = true
+		if !p.unrepresentableIdentifiers[name] {
+			p.unrepresentableIdentifiers[name] = true
+			where, notes := p.prettyPrintTargetEnvironment(compat.UpdatedIdentifiers)
 			r := js_lexer.RangeOfIdentifier(p.source, loc)
-			p.log.AddRangeError(&p.tracker, r, fmt.Sprintf("%q cannot be escaped in the target environment ("+
-				"consider setting the charset to \"utf8\" or changing the target)", name))
+			p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf("%q cannot be escaped in %s but you "+
+				"can set the charset to \"utf8\" to allow unescaped Unicode characters", name, where), notes)
+		}
+	} else if p.options.unsupportedJSFeatures.Has(compat.UpdatedIdentifiers) && !strings.HasPrefix(name, "#") &&
+		!js_lexer.IsIdentifier(name, p.options.unsupportedJSFeatures) {
+		if p.unrepresentableIdentifiers == nil {
+			p.unrepresentableIdentifiers = make(map[string]bool)
+		}
+		if !p.unrepresentableIdentifiers[name] {
+			p.unrepresentableIdentifiers[name] = true
+			where, notes := p.prettyPrintTargetEnvironment(compat.UpdatedIdentifiers)
+			r := js_lexer.RangeOfIdentifier(p.source, loc)
+			p.log.AddRangeErrorWithNotes(&p.tracker, r, fmt.Sprintf("%q is not considered a valid identifier in %s", name, where), notes)
 		}
 	}
 }
@@ -11263,7 +11275,7 @@ func (p *parser) visitExprInOut(expr js_ast.Expr, in exprIn) (js_ast.Expr, exprO
 
 		// "a['b']" => "a.b"
 		if p.options.mangleSyntax {
-			if str, ok := e.Index.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value) {
+			if str, ok := e.Index.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value, 0) {
 				dot := &js_ast.EDot{
 					Target:        e.Target,
 					Name:          js_lexer.UTF16ToString(str.Value),
@@ -11747,7 +11759,7 @@ func (p *parser) visitExprInOut(expr js_ast.Expr, in exprIn) (js_ast.Expr, exprO
 
 				// "{['x']: y}" => "{x: y}"
 				if p.options.mangleSyntax && property.IsComputed {
-					if str, ok := key.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value) && !js_lexer.UTF16EqualsString(str.Value, "__proto__") {
+					if str, ok := key.Data.(*js_ast.EString); ok && js_lexer.IsIdentifierUTF16(str.Value, 0) && !js_lexer.UTF16EqualsString(str.Value, "__proto__") {
 						property.IsComputed = false
 					}
 				}
@@ -13861,7 +13873,7 @@ func ParseJSXExpr(text string, kind JSXExprKind) (config.JSXExpr, bool) {
 	// Try a property chain
 	parts := strings.Split(text, ".")
 	for _, part := range parts {
-		if !js_lexer.IsIdentifier(part) {
+		if !js_lexer.IsIdentifier(part, 0) {
 			parts = nil
 			break
 		}
diff --git a/internal/js_parser/js_parser_lower.go b/internal/js_parser/js_parser_lower.go
index e08aa86e60d..524314e4130 100644
--- a/internal/js_parser/js_parser_lower.go
+++ b/internal/js_parser/js_parser_lower.go
@@ -14,6 +14,19 @@ import (
 	"github.com/evanw/esbuild/internal/logger"
 )
 
+func (p *parser) prettyPrintTargetEnvironment(feature compat.JSFeature) (where string, notes []logger.MsgData) {
+	where = "the configured target environment"
+	if tsTarget := p.options.tsTarget; tsTarget != nil && tsTarget.UnsupportedJSFeatures.Has(feature) {
+		tracker := logger.MakeLineColumnTracker(&tsTarget.Source)
+		where = fmt.Sprintf("%s (%q)", where, tsTarget.Target)
+		notes = []logger.MsgData{logger.RangeData(&tracker, tsTarget.Range, fmt.Sprintf(
+			"The target environment was set to %q here", tsTarget.Target))}
+	} else if p.options.originalTargetEnv != "" {
+		where = fmt.Sprintf("%s (%s)", where, p.options.originalTargetEnv)
+	}
+	return
+}
+
 func (p *parser) markSyntaxFeature(feature compat.JSFeature, r logger.Range) (didGenerateError bool) {
 	didGenerateError = true
 
@@ -29,17 +42,7 @@ func (p *parser) markSyntaxFeature(feature compat.JSFeature, r logger.Range) (di
 	}
 
 	var name string
-	var notes []logger.MsgData
-	where := "the configured target environment"
-
-	if tsTarget := p.options.tsTarget; tsTarget != nil && tsTarget.UnsupportedJSFeatures.Has(feature) {
-		tracker := logger.MakeLineColumnTracker(&tsTarget.Source)
-		where = fmt.Sprintf("%s (%q)", where, tsTarget.Target)
-		notes = []logger.MsgData{logger.RangeData(&tracker, tsTarget.Range, fmt.Sprintf(
-			"The target environment was set to %q here", tsTarget.Target))}
-	} else if p.options.originalTargetEnv != "" {
-		where = fmt.Sprintf("%s (%s)", where, p.options.originalTargetEnv)
-	}
+	where, notes := p.prettyPrintTargetEnvironment(feature)
 
 	switch feature {
 	case compat.DefaultArgument:
diff --git a/internal/js_parser/js_parser_test.go b/internal/js_parser/js_parser_test.go
index a76d86fd9a1..1df90c115aa 100644
--- a/internal/js_parser/js_parser_test.go
+++ b/internal/js_parser/js_parser_test.go
@@ -149,6 +149,30 @@ func expectPrintedJSX(t *testing.T, contents string, expected string) {
 	})
 }
 
+func expectParseErrorTargetJSX(t *testing.T, esVersion int, contents string, expected string) {
+	t.Helper()
+	expectParseErrorCommon(t, contents, expected, config.Options{
+		UnsupportedJSFeatures: compat.UnsupportedJSFeatures(map[compat.Engine][]int{
+			compat.ES: {esVersion},
+		}),
+		JSX: config.JSXOptions{
+			Parse: true,
+		},
+	})
+}
+
+func expectPrintedTargetJSX(t *testing.T, esVersion int, contents string, expected string) {
+	t.Helper()
+	expectPrintedCommon(t, contents, expected, config.Options{
+		UnsupportedJSFeatures: compat.UnsupportedJSFeatures(map[compat.Engine][]int{
+			compat.ES: {esVersion},
+		}),
+		JSX: config.JSXOptions{
+			Parse: true,
+		},
+	})
+}
+
 func TestBinOp(t *testing.T) {
 	for code, entry := range js_ast.OpTable {
 		opCode := js_ast.OpCode(code)
@@ -4606,8 +4630,8 @@ func TestES5(t *testing.T) {
 }
 
 func TestASCIIOnly(t *testing.T) {
-	es5 := "<stdin>: error: \"𐀀\" cannot be escaped in the target environment " +
-		"(consider setting the charset to \"utf8\" or changing the target)\n"
+	es5 := "<stdin>: error: \"𐀀\" cannot be escaped in the configured target environment " +
+		"but you can set the charset to \"utf8\" to allow unescaped Unicode characters\n"
 
 	// Some context: "π" is in the BMP (i.e. has a code point ≤0xFFFF) and "𐀀" is
 	// not in the BMP (i.e. has a code point >0xFFFF). This distinction matters
@@ -4753,3 +4777,24 @@ func TestASCIIOnly(t *testing.T) {
 	expectPrintedTargetASCII(t, 5, "export var π", "export var \\u03C0;\n")
 	expectParseErrorTargetASCII(t, 5, "export var 𐀀", es5)
 }
+
+func TestUpdatedIdentifiers(t *testing.T) {
+	// Some context: The text "ꓷꓶꓲꓵꓭꓢꓱ" is all non-BMP code points and is a valid
+	// identifier in ES6+ but not in ES5. It must either be quoted or forbidden
+	// when it's used in ES5.
+
+	expectPrinted(t, "x.ꓷꓶꓲꓵꓭꓢꓱ", "x.ꓷꓶꓲꓵꓭꓢꓱ;\n")
+	expectPrinted(t, "var ꓷꓶꓲꓵꓭꓢꓱ", "var ꓷꓶꓲꓵꓭꓢꓱ;\n")
+	expectPrintedTarget(t, 5, "x.ꓷꓶꓲꓵꓭꓢꓱ", "x[\"ꓷꓶꓲꓵꓭꓢꓱ\"];\n")
+	expectPrintedTarget(t, 5, "x = {ꓷꓶꓲꓵꓭꓢꓱ: 0}", "x = { \"ꓷꓶꓲꓵꓭꓢꓱ\": 0 };\n")
+	expectParseErrorTarget(t, 5, "ꓷꓶꓲꓵꓭꓢꓱ",
+		"<stdin>: error: \"ꓷꓶꓲꓵꓭꓢꓱ\" is not considered a valid identifier in the configured target environment\n")
+	expectParseErrorTarget(t, 5, "var ꓷꓶꓲꓵꓭꓢꓱ",
+		"<stdin>: error: \"ꓷꓶꓲꓵꓭꓢꓱ\" is not considered a valid identifier in the configured target environment\n")
+
+	expectPrintedJSX(t, "<x ꓷꓶꓲꓵꓭꓢꓱ/>", "/* @__PURE__ */ React.createElement(\"x\", {\n  ꓷꓶꓲꓵꓭꓢꓱ: true\n});\n")
+	expectPrintedJSX(t, "<ꓷꓶꓲꓵꓭꓢꓱ/>", "/* @__PURE__ */ React.createElement(ꓷꓶꓲꓵꓭꓢꓱ, null);\n")
+	expectPrintedTargetJSX(t, 5, "<x ꓷꓶꓲꓵꓭꓢꓱ/>", "/* @__PURE__ */ React.createElement(\"x\", {\n  \"ꓷꓶꓲꓵꓭꓢꓱ\": true\n});\n")
+	expectParseErrorTargetJSX(t, 5, "<ꓷꓶꓲꓵꓭꓢꓱ/>",
+		"<stdin>: error: \"ꓷꓶꓲꓵꓭꓢꓱ\" is not considered a valid identifier in the configured target environment\n")
+}
diff --git a/internal/js_parser/ts_parser.go b/internal/js_parser/ts_parser.go
index 6485eaf31d6..582e2c09aea 100644
--- a/internal/js_parser/ts_parser.go
+++ b/internal/js_parser/ts_parser.go
@@ -842,7 +842,7 @@ func (p *parser) parseTypeScriptEnumStmt(loc logger.Loc, opts parseStmtOpts) js_
 		p.lexer.Next()
 
 		// Identifiers can be referenced by other values
-		if !opts.isTypeScriptDeclare && js_lexer.IsIdentifierUTF16(value.Name) {
+		if !opts.isTypeScriptDeclare && js_lexer.IsIdentifierUTF16(value.Name, 0) {
 			value.Ref = p.declareSymbol(js_ast.SymbolOther, value.Loc, js_lexer.UTF16ToString(value.Name))
 		}
 
diff --git a/internal/js_printer/js_printer.go b/internal/js_printer/js_printer.go
index 1bc89293b90..4f541c5b9e9 100644
--- a/internal/js_printer/js_printer.go
+++ b/internal/js_printer/js_printer.go
@@ -805,7 +805,7 @@ func (p *printer) printSymbol(ref js_ast.Ref) {
 }
 
 func (p *printer) printClauseAlias(alias string) {
-	if js_lexer.IsIdentifier(alias) {
+	if js_lexer.IsIdentifier(alias, p.options.UnsupportedFeatures) {
 		p.printSpaceBeforeIdentifier()
 		p.printIdentifier(alias)
 	} else {
@@ -814,19 +814,19 @@ func (p *printer) printClauseAlias(alias string) {
 }
 
 func CanQuoteIdentifier(name string, unsupportedJSFeatures compat.JSFeature, asciiOnly bool) bool {
-	return js_lexer.IsIdentifier(name) && (!asciiOnly ||
+	return js_lexer.IsIdentifier(name, unsupportedJSFeatures) && (!asciiOnly ||
 		!unsupportedJSFeatures.Has(compat.UnicodeEscapes) ||
 		!js_lexer.ContainsNonBMPCodePoint(name))
 }
 
 func (p *printer) canPrintIdentifier(name string) bool {
-	return js_lexer.IsIdentifier(name) && (!p.options.ASCIIOnly ||
+	return js_lexer.IsIdentifier(name, p.options.UnsupportedFeatures) && (!p.options.ASCIIOnly ||
 		!p.options.UnsupportedFeatures.Has(compat.UnicodeEscapes) ||
 		!js_lexer.ContainsNonBMPCodePoint(name))
 }
 
 func (p *printer) canPrintIdentifierUTF16(name []uint16) bool {
-	return js_lexer.IsIdentifierUTF16(name) && (!p.options.ASCIIOnly ||
+	return js_lexer.IsIdentifierUTF16(name, p.options.UnsupportedFeatures) && (!p.options.ASCIIOnly ||
 		!p.options.UnsupportedFeatures.Has(compat.UnicodeEscapes) ||
 		!js_lexer.ContainsNonBMPCodePointUTF16(name))
 }
@@ -1058,7 +1058,7 @@ func (p *printer) printSemicolonIfNeeded() {
 func (p *printer) printSpaceBeforeIdentifier() {
 	buffer := p.js
 	n := len(buffer)
-	if n > 0 && (js_lexer.IsIdentifierContinue(rune(buffer[n-1])) || n == p.prevRegExpEnd) {
+	if n > 0 && (js_lexer.IsIdentifierContinue(rune(buffer[n-1]), 0) || n == p.prevRegExpEnd) {
 		p.print(" ")
 	}
 }
diff --git a/internal/renamer/renamer.go b/internal/renamer/renamer.go
index 866a817599b..04cf254e963 100644
--- a/internal/renamer/renamer.go
+++ b/internal/renamer/renamer.go
@@ -8,6 +8,7 @@ import (
 	"sync/atomic"
 
 	"github.com/evanw/esbuild/internal/ast"
+	"github.com/evanw/esbuild/internal/compat"
 	"github.com/evanw/esbuild/internal/js_ast"
 	"github.com/evanw/esbuild/internal/js_lexer"
 )
@@ -386,12 +387,13 @@ func (a slotAndCountArray) Less(i int, j int) bool {
 // NumberRenamer
 
 type NumberRenamer struct {
-	symbols js_ast.SymbolMap
-	names   [][]string
-	root    numberScope
+	symbols               js_ast.SymbolMap
+	names                 [][]string
+	root                  numberScope
+	unsupportedJSFeatures compat.JSFeature
 }
 
-func NewNumberRenamer(symbols js_ast.SymbolMap, reservedNames map[string]uint32) *NumberRenamer {
+func NewNumberRenamer(symbols js_ast.SymbolMap, reservedNames map[string]uint32, unsupportedJSFeatures compat.JSFeature) *NumberRenamer {
 	return &NumberRenamer{
 		symbols: symbols,
 		names:   make([][]string, len(symbols.SymbolsForSource)),
@@ -437,7 +439,7 @@ func (r *NumberRenamer) assignName(scope *numberScope, ref js_ast.Ref) {
 	}
 
 	// Compute a new name
-	name := scope.findUnusedName(originalName)
+	name := scope.findUnusedName(originalName, r.unsupportedJSFeatures)
 
 	// Store the new name
 	if inner == nil {
@@ -534,8 +536,8 @@ func (s *numberScope) findNameUse(name string) nameUse {
 	}
 }
 
-func (s *numberScope) findUnusedName(name string) string {
-	name = js_lexer.ForceValidIdentifier(name)
+func (s *numberScope) findUnusedName(name string, unsupportedJSFeatures compat.JSFeature) string {
+	name = js_lexer.ForceValidIdentifier(name, unsupportedJSFeatures)
 
 	if use := s.findNameUse(name); use != nameUnused {
 		// If the name is already in use, generate a new name by appending a number
diff --git a/internal/resolver/tsconfig_json.go b/internal/resolver/tsconfig_json.go
index 9897732e928..fefa6b8e7cf 100644
--- a/internal/resolver/tsconfig_json.go
+++ b/internal/resolver/tsconfig_json.go
@@ -234,7 +234,7 @@ func parseMemberExpressionForJSX(log logger.Log, source *logger.Source, tracker
 	}
 	parts := strings.Split(text, ".")
 	for _, part := range parts {
-		if !js_lexer.IsIdentifier(part) {
+		if !js_lexer.IsIdentifier(part, 0) {
 			warnRange := source.RangeOfString(loc)
 			log.AddRangeWarning(tracker, warnRange, fmt.Sprintf("Invalid JSX member expression: %q", text))
 			return nil
diff --git a/pkg/api/api_impl.go b/pkg/api/api_impl.go
index 89a4e9d612e..5fe3d9301c1 100644
--- a/pkg/api/api_impl.go
+++ b/pkg/api/api_impl.go
@@ -438,7 +438,7 @@ func validateDefines(
 	for key, value := range defines {
 		// The key must be a dot-separated identifier list
 		for _, part := range strings.Split(key, ".") {
-			if !js_lexer.IsIdentifier(part) {
+			if !js_lexer.IsIdentifier(part, 0) {
 				if part == key {
 					log.AddError(nil, logger.Loc{}, fmt.Sprintf("The define key %q must be a valid identifier", key))
 				} else {
@@ -449,7 +449,7 @@ func validateDefines(
 		}
 
 		// Allow substituting for an identifier
-		if js_lexer.IsIdentifier(value) {
+		if js_lexer.IsIdentifier(value, 0) {
 			if _, ok := js_lexer.Keywords[value]; !ok {
 				name := value // The closure must close over a variable inside the loop
 				rawDefines[key] = config.DefineData{
@@ -538,7 +538,7 @@ func validateDefines(
 	for _, key := range pureFns {
 		// The key must be a dot-separated identifier list
 		for _, part := range strings.Split(key, ".") {
-			if !js_lexer.IsIdentifier(part) {
+			if !js_lexer.IsIdentifier(part, 0) {
 				log.AddError(nil, logger.Loc{}, fmt.Sprintf("Invalid pure function: %q", key))
 				continue
 			}
diff --git a/scripts/compat-table.js b/scripts/compat-table.js
index a29e12ff466..98cc53952d1 100644
--- a/scripts/compat-table.js
+++ b/scripts/compat-table.js
@@ -37,6 +37,7 @@ const features = {
   'class': { target: 'Class' },
   'generators': { target: 'Generator' },
   'Unicode code point escapes': { target: 'UnicodeEscapes' },
+  'Updated identifier syntax': { target: 'UpdatedIdentifiers' },
 
   // >ES6 features
   'exponentiation (**) operator': { target: 'ExponentOperator' },
@@ -140,6 +141,7 @@ mergeVersions('ObjectExtensions', { es2015: true })
 mergeVersions('RestArgument', { es2015: true })
 mergeVersions('TemplateLiteral', { es2015: true })
 mergeVersions('UnicodeEscapes', { es2015: true })
+mergeVersions('UpdatedIdentifiers', { es2015: true })
 
 // >ES6 features
 mergeVersions('ExponentOperator', { es2016: true })
diff --git a/scripts/gen-unicode-table.js b/scripts/gen-unicode-table.js
index 6afbf6d383c..eaffeb2947d 100644
--- a/scripts/gen-unicode-table.js
+++ b/scripts/gen-unicode-table.js
@@ -1,8 +1,49 @@
 const fs = require('fs');
 const path = require('path');
-const version = '@unicode/unicode-13.0.0';
-const idStart = require(`${version}/Binary_Property/ID_Start/code-points`);
-const idContinue = require(`${version}/Binary_Property/ID_Continue/code-points`);
+
+// ES5 reference: https://es5.github.io/
+//
+// A conforming implementation of this International standard shall interpret
+// characters in conformance with the Unicode Standard, Version 3.0 or later
+// and ISO/IEC 10646-1 with either UCS-2 or UTF-16 as the adopted encoding
+// form, implementation level 3. If the adopted ISO/IEC 10646-1 subset is not
+// otherwise specified, it is presumed to be the BMP subset, collection 300.
+//
+// UnicodeLetter: any character in the Unicode categories “Uppercase letter (Lu)”,
+// “Lowercase letter (Ll)”, “Titlecase letter (Lt)”, “Modifier letter (Lm)”,
+// “Other letter (Lo)”, or “Letter number (Nl)”.
+const idStartES5 = [].concat(
+  require('@unicode/unicode-3.0.0/General_Category/Uppercase_Letter/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Lowercase_Letter/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Titlecase_Letter/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Modifier_Letter/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Other_Letter/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Letter_Number/code-points'),
+).sort((a, b) => a - b)
+
+// UnicodeCombiningMark: any character in the Unicode categories “Non-spacing mark (Mn)”
+// or “Combining spacing mark (Mc)”
+// UnicodeDigit: any character in the Unicode category “Decimal number (Nd)”
+// UnicodeConnectorPunctuation: any character in the Unicode category “Connector punctuation (Pc)”
+const idContinueES5 = idStartES5.concat(
+  require('@unicode/unicode-3.0.0/General_Category/Nonspacing_Mark/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Spacing_Mark/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Decimal_Number/code-points'),
+  require('@unicode/unicode-3.0.0/General_Category/Connector_Punctuation/code-points'),
+).sort((a, b) => a - b)
+
+// ESNext reference: https://tc39.es/ecma262/
+//
+// A conforming implementation of ECMAScript must interpret source text input
+// in conformance with the Unicode Standard, Version 5.1.0 or later and ISO/IEC
+// 10646. If the adopted ISO/IEC 10646-1 subset is not otherwise specified, it
+// is presumed to be the Unicode set, collection 10646.
+//
+// UnicodeIDStart: any Unicode code point with the Unicode property “ID_Start”
+const idStart = require('@unicode/unicode-13.0.0/Binary_Property/ID_Start/code-points');
+
+// UnicodeIDContinue: any Unicode code point with the Unicode property “ID_Continue”
+const idContinue = require('@unicode/unicode-13.0.0/Binary_Property/ID_Continue/code-points');
 
 function generateRangeTable(codePoints) {
   let lines = [];
@@ -59,6 +100,10 @@ package js_lexer
 
 import "unicode"
 
+var idStartES5 = ${generateRangeTable(idStartES5)}
+
+var idContinueES5 = ${generateRangeTable(idContinueES5)}
+
 var idStart = ${generateRangeTable(idStart)}
 
 var idContinue = ${generateRangeTable(idContinue)}
diff --git a/scripts/package-lock.json b/scripts/package-lock.json
index 6ec296a0b34..b71d4e24610 100644
--- a/scripts/package-lock.json
+++ b/scripts/package-lock.json
@@ -7,6 +7,7 @@
       "dependencies": {
         "@types/node": "14.14.6",
         "@unicode/unicode-13.0.0": "1.0.6",
+        "@unicode/unicode-3.0.0": "1.0.6",
         "fuse.js": "3.2.0",
         "js-yaml": "3.14.0",
         "react": "17.0.1",
@@ -24,6 +25,11 @@
       "resolved": "https://registry.npmjs.org/@unicode/unicode-13.0.0/-/unicode-13.0.0-1.0.6.tgz",
       "integrity": "sha512-ywSlML1wdeBSGH12b6PkblGtjzsQNMZ7+JlJj+eoPj0VuCeg52hcUTeVWfd4GmISU+zOQHWjNC6c0xmsIuVy8Q=="
     },
+    "node_modules/@unicode/unicode-3.0.0": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/@unicode/unicode-3.0.0/-/unicode-3.0.0-1.0.6.tgz",
+      "integrity": "sha512-eHhtHouHRCE3r0Sq4Spp/P6z1S000pEYkimT2d1xRoYrUDBUJ2TXbIfn96DgdslhBDtoIrnq2kdsCHWnh5RmBg=="
+    },
     "node_modules/argparse": {
       "version": "1.0.10",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
@@ -134,6 +140,11 @@
       "resolved": "https://registry.npmjs.org/@unicode/unicode-13.0.0/-/unicode-13.0.0-1.0.6.tgz",
       "integrity": "sha512-ywSlML1wdeBSGH12b6PkblGtjzsQNMZ7+JlJj+eoPj0VuCeg52hcUTeVWfd4GmISU+zOQHWjNC6c0xmsIuVy8Q=="
     },
+    "@unicode/unicode-3.0.0": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/@unicode/unicode-3.0.0/-/unicode-3.0.0-1.0.6.tgz",
+      "integrity": "sha512-eHhtHouHRCE3r0Sq4Spp/P6z1S000pEYkimT2d1xRoYrUDBUJ2TXbIfn96DgdslhBDtoIrnq2kdsCHWnh5RmBg=="
+    },
     "argparse": {
       "version": "1.0.10",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
diff --git a/scripts/package.json b/scripts/package.json
index 0bafdae32d8..4451f22250c 100644
--- a/scripts/package.json
+++ b/scripts/package.json
@@ -2,6 +2,7 @@
   "dependencies": {
     "@types/node": "14.14.6",
     "@unicode/unicode-13.0.0": "1.0.6",
+    "@unicode/unicode-3.0.0": "1.0.6",
     "fuse.js": "3.2.0",
     "js-yaml": "3.14.0",
     "react": "17.0.1",