Update: Add exceptionPatterns to id-length rule (fixes #13094)

docs/rules/id-length.md

@@ -82,6 +82,7 @@ This rule has an object option:
 * `"properties": always` (default) enforces identifier length convention for property names
 * `"properties": never` ignores identifier length convention for property names
 * `"exceptions"` allows an array of specified identifier names
+* `"exceptionPatterns"` array of strings representing regular expression patterns, allows identifiers that match any of the patterns.
 
 ### min
 
@@ -217,6 +218,29 @@ const { x } = foo;
 const { a: x } = foo;
 ```
 
+### exceptionPatterns
+
+Examples of additional **correct** code for this rule with the `{ "exceptionPatterns": ["E|S", "[x-z]"] }` option:
+
+```js
+/*eslint id-length: ["error", { "exceptionPatterns": ["E|S", "[x-z]"] }]*/
+/*eslint-env es6*/
+
+var E = 5;
+function S() { return 42; }
+obj.x = document.body;
+var foo = function (x) { /* do stuff */ };
+try {
+    dangerousStuff();
+} catch (x) {
+    // ignore as many do
+}
+(y) => {return  y * y};
+var [E] = arr;
+const { y } = foo;
+const { a: z } = foo;
+```
+
 ## Related Rules
 
 * [max-len](max-len.md)

lib/rules/id-length.js

@@ -39,6 +39,13 @@ module.exports = {
                             type: "string"
                         }
                     },
+                    exceptionPatterns: {
+                        type: "array",
+                        uniqueItems: true,
+                        items: {
+                            type: "string"
+                        }
+                    },
                     properties: {
                         enum: ["always", "never"]
                     }
@@ -63,8 +70,19 @@ module.exports = {
 
                 return obj;
             }, {});
+        const exceptionPatterns = (options.exceptionPatterns || []).map(pattern => new RegExp(pattern, "u"));
         const reportedNode = new Set();
 
+        /**
+         * Checks if a string matches the provided exception patterns
+         * @param {string} name The string to check.
+         * @returns {boolean} if the string is a match
+         * @private
+         */
+        function matchesExceptionPattern(name) {
+            return exceptionPatterns.some(pattern => pattern.test(name));
+        }
+
         const SUPPORTED_EXPRESSIONS = {
             MemberExpression: properties && function(parent) {
                 return !parent.computed && (
@@ -112,7 +130,7 @@ module.exports = {
                 const isShort = name.length < minLength;
                 const isLong = name.length > maxLength;
 
-                if (!(isShort || isLong) || exceptions[name]) {
+                if (!(isShort || isLong) || exceptions[name] || matchesExceptionPattern(name)) {
                     return; // Nothing to report
                 }
 

tests/lib/rules/id-length.js

@@ -77,7 +77,12 @@ ruleTester.run("id-length", rule, {
         { code: "var {x} = foo;", options: [{ properties: "never" }], parserOptions: { ecmaVersion: 6 } },
         { code: "var {x, y: {z}} = foo;", options: [{ properties: "never" }], parserOptions: { ecmaVersion: 6 } },
         { code: "let foo = { [a]: 1 };", options: [{ properties: "always" }], parserOptions: { ecmaVersion: 6 } },
-        { code: "let foo = { [a + b]: 1 };", options: [{ properties: "always" }], parserOptions: { ecmaVersion: 6 } }
+        { code: "let foo = { [a + b]: 1 };", options: [{ properties: "always" }], parserOptions: { ecmaVersion: 6 } },
+        { code: "function BEFORE_send() {};", options: [{ min: 3, max: 5, exceptionPatterns: ["^BEFORE_"] }] },
+        { code: "function BEFORE_send() {};", options: [{ min: 3, max: 5, exceptionPatterns: ["^BEFORE_", "send$"] }] },
+        { code: "function BEFORE_send() {};", options: [{ min: 3, max: 5, exceptionPatterns: ["^BEFORE_", "^A", "^Z"] }] },
+        { code: "function BEFORE_send() {};", options: [{ min: 3, max: 5, exceptionPatterns: ["^A", "^BEFORE_", "^Z"] }] },
+        { code: "var x = 1 ;", options: [{ min: 3, max: 5, exceptionPatterns: ["[x-z]"] }] }
     ],
     invalid: [
         { code: "var x = 1;", errors: [tooShortError] },
@@ -440,6 +445,27 @@ ruleTester.run("id-length", rule, {
             errors: [
                 tooShortError
             ]
+        },
+        {
+            code: "function BEFORE_send() {};",
+            options: [{ min: 3, max: 5 }],
+            errors: [
+                tooLongError
+            ]
+        },
+        {
+            code: "function NOTMATCHED_send() {};",
+            options: [{ min: 3, max: 5, exceptionPatterns: ["^BEFORE_"] }],
+            errors: [
+                tooLongError
+            ]
+        },
+        {
+            code: "function N() {};",
+            options: [{ min: 3, max: 5, exceptionPatterns: ["^BEFORE_"] }],
+            errors: [
+                tooShortError
+            ]
         }
     ]
 });