Fix bug

sindresorhus · May 3, 2020 · b6f1571 · b6f1571
1 parent 09a24bb
commit b6f1571
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Showing 2 changed files with 39 additions and 4 deletions.
diff --git a/rules/prefer-string-slice.js b/rules/prefer-string-slice.js
@@ -71,7 +71,14 @@ const create = context => {
 				sliceArguments = [firstArgument];
 			} else if (argumentNodes.length === 2) {
 				if (firstArgument === '0') {
-					sliceArguments = [firstArgument, secondArgument];
+					sliceArguments = [firstArgument];
+					if (isLiteralNumber(secondArgument) || isLengthProperty(argumentNodes[1])) {
+						sliceArguments.push(secondArgument)
+					} else if (getNumericValue(argumentNodes[1]) !== undefined) {
+						sliceArguments.push(Math.max(0, getNumericValue(argumentNodes[1])))
+					} else {
+						sliceArguments.push(`Math.max(0, ${secondArgument})`)
+					}
 				} else if (
 					isLiteralNumber(argumentNodes[0]) &&
 					isLiteralNumber(argumentNodes[1])
@@ -124,7 +131,7 @@ const create = context => {
 					sliceArguments = [`Math.max(0, ${firstArgument})`];
 				}
 			} else if (argumentNodes.length === 2) {
-				const secondNumber = argumentNodes[1] ? getNumericValue(argumentNodes[1]) : undefined;
+				const secondNumber = getNumericValue(argumentNodes[1]);
 
 				if (firstNumber !== undefined && secondNumber !== undefined) {
 					sliceArguments = firstNumber > secondNumber ?

diff --git a/test/prefer-string-slice.js b/test/prefer-string-slice.js
@@ -84,7 +84,7 @@ ruleTester.run('prefer-string-slice', rule, {
 			`,
 			output: outdent`
 				const length = 123;
-				"foo".slice(0, length)
+				"foo".slice(0, Math.max(0, length))
 			`,
 			errors
 		},
@@ -99,6 +99,16 @@ ruleTester.run('prefer-string-slice', rule, {
 			`,
 			errors
 		},
+		{
+			code: '"foo".substr(0, -1)',
+			output: '"foo".slice(0, 0)',
+			errors
+		},
+		{
+			code: '"foo".substr(0, "foo".length)',
+			output: '"foo".slice(0, "foo".length)',
+			errors
+		},
 		{
 			code: outdent`
 				const length = 123;
@@ -138,6 +148,18 @@ ruleTester.run('prefer-string-slice', rule, {
 			code: '"foo".substr(1, 2)',
 			errors
 		},
+		// Extra arguments
+		{
+			code: 'foo.substr(1, 2, 3)',
+			output: 'foo.substr(1, 2, 3)',
+			errors
+		},
+		// #700
+		{
+			code: '"Sample".substr(0, "Sample".lastIndexOf("/"))',
+			output: '"Sample".slice(0, Math.max(0, "Sample".lastIndexOf("/")))',
+			errors
+		},
 
 		{
 			code: 'foo.substring()',
@@ -210,7 +232,13 @@ ruleTester.run('prefer-string-slice', rule, {
 		{
 			code: '"foo".substring(1, 3)',
 			errors
-		}
+		},
+		// Extra arguments
+		{
+			code: 'foo.substring(1, 2, 3)',
+			output: 'foo.substring(1, 2, 3)',
+			errors
+		},
 	]
 });