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Update: add new ignore pattern options to no-unused-vars (fixes #2321)
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‎docs/rules/no-unused-vars.md‎

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@@ -98,6 +98,51 @@ The following code:
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})();
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```
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#### Ignore identifiers that match specific patterns
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* `varsIgnorePattern` - all variables that match this regexp pattern will not be checked.
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* `argsIgnorePattern` - all arguments that match this regexp pattern will not be checked.
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##### Examples
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* Ignore all unused function arguments with a leading underscore
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```json
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{
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"rules": {
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"no-unused-vars": [2, {"args": "after-used", "argsIgnorePattern": "^_"}]
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}
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}
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```
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With this configuration, this rule will not warn about the following code:
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```js
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function foo(x, _y) {
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return x + 1;
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}
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foo();
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```
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* Ignore all unused variables which contain the term `ignored` or `Ignored`:
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```json
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{
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"ecmaFeatures": { "destructuring": true },
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"rules": {
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"no-unused-vars": [2, {"vars": "all", "varsIgnorePattern": "[iI]gnored"}]
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}
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}
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```
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With this configuration, this rule will not warn about the following code:
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```js
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var [ firstItemIgnored, secondItem ] = items;
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console.log(secondItem);
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```
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## When Not to Use It
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If you don't want to be notified about unused variables or function arguments, you can safely turn this rule off.

‎lib/rules/no-unused-vars.js‎

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@@ -18,20 +18,29 @@ module.exports = function(context) {
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args: "after-used"
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};
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if (context.options[0]) {
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if (typeof context.options[0] === "string") {
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config.vars = context.options[0];
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var firstOption = context.options[0];
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if (firstOption) {
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if (typeof firstOption === "string") {
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config.vars = firstOption;
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} else {
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config.vars = context.options[0].vars || config.vars;
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config.args = context.options[0].args || config.args;
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config.vars = firstOption.vars || config.vars;
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config.args = firstOption.args || config.args;
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if (firstOption.varsIgnorePattern) {
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config.varsIgnorePattern = new RegExp(firstOption.varsIgnorePattern);
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}
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if (firstOption.argsIgnorePattern) {
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config.argsIgnorePattern = new RegExp(firstOption.argsIgnorePattern);
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}
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}
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}
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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/**
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* Determines if a given variable is being exported from a module.
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* @param {Variable} variable - EScope variable object.
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continue;
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}
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// skip any setter argument
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if (type === "Parameter" && def.node.parent.type === "Property" && def.node.parent.kind === "set") {
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continue;
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}
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// if "args" option is "none", skip any parameter
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if (config.args === "none" && type === "Parameter") {
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continue;
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}
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// if "args" option is "after-used", skip all but the last parameter
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if (config.args === "after-used" && type === "Parameter" && def.index < def.node.params.length - 1) {
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continue;
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if (type === "Parameter") {
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// skip any setter argument
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if (def.node.parent.type === "Property" && def.node.parent.kind === "set") {
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continue;
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}
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// if "args" option is "none", skip any parameter
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if (config.args === "none") {
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continue;
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}
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// skip ignored parameters
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if (config.argsIgnorePattern && config.argsIgnorePattern.test(def.name.name)) {
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continue;
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}
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// if "args" option is "after-used", skip all but the last parameter
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if (config.args === "after-used" && def.index < def.node.params.length - 1) {
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continue;
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}
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} else {
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// skip ignored variables
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if (config.varsIgnorePattern && config.varsIgnorePattern.test(def.name.name)) {
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continue;
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}
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}
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}
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@@ -244,8 +265,14 @@ module.exports.schema = [
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"vars": {
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"enum": ["all", "local"]
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},
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"varsIgnorePattern": {
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"type": "string"
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},
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"args": {
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"enum": ["all", "after-used", "none"]
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},
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"argsIgnorePattern": {
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"type": "string"
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}
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}
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}

‎tests/lib/rules/no-unused-vars.js‎

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@@ -111,7 +111,14 @@ ruleTester.run("no-unused-vars", rule, {
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// Can mark variables as used via context.markVariableAsUsed()
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{ code: "/*eslint use-every-a:1*/ var a;"},
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{ code: "/*eslint use-every-a:1*/ !function(a) { return 1; }"},
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{ code: "/*eslint use-every-a:1*/ !function() { var a; return 1 }"}
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{ code: "/*eslint use-every-a:1*/ !function() { var a; return 1 }"},
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// ignore pattern
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{ code: "var _a;", options: [ { vars: "all", varsIgnorePattern: "^_" } ] },
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{ code: "var a; function foo() { var _b; } foo();", options: [ { vars: "local", varsIgnorePattern: "^_" } ] },
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{ code: "function foo(_a) { } foo();", options: [ { args: "all", argsIgnorePattern: "^_" } ] },
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{ code: "function foo(a, _b) { return a; } foo();", options: [ { args: "after-used", argsIgnorePattern: "^_" } ] },
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{ code: "var [ firstItemIgnored, secondItem ] = items;\nconsole.log(secondItem);", ecmaFeatures: {destructuring: true}, options: [ { vars: "all", varsIgnorePattern: "[iI]gnored" } ] }
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],
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invalid: [
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{ code: "function foox() { return foox(); }", errors: [{ message: "foox is defined but never used", type: "Identifier"}] },
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// exported
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{ code: "/*exported max*/ var max = 1, min = {min: 1}", errors: [{ message: "min is defined but never used" }] },
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{ code: "/*exported x*/ var { x, y } = z", ecmaFeatures: { destructuring: true }, errors: [{ message: "y is defined but never used" }] }
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{ code: "/*exported x*/ var { x, y } = z", ecmaFeatures: { destructuring: true }, errors: [{ message: "y is defined but never used" }] },
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// ignore pattern
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{ code: "var _a; var b;", options: [ { vars: "all", varsIgnorePattern: "^_" } ], errors: [{ message: "b is defined but never used", line: 1, column: 13 }] },
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{ code: "var a; function foo() { var _b; var c_; } foo();", options: [ { vars: "local", varsIgnorePattern: "^_" } ], errors: [{ message: "c_ is defined but never used", line: 1, column: 37 }] },
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{ code: "function foo(a, _b) { } foo();", options: [ { args: "all", argsIgnorePattern: "^_" } ], errors: [{ message: "a is defined but never used", line: 1, column: 14 }] },
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{ code: "function foo(a, _b, c) { return a; } foo();", options: [ { args: "after-used", argsIgnorePattern: "^_" } ], errors: [{ message: "c is defined but never used", line: 1, column: 21 }] },
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{ code: "var [ firstItemIgnored, secondItem ] = items;", ecmaFeatures: {destructuring: true}, options: [ { vars: "all", varsIgnorePattern: "[iI]gnored" } ], errors: [{ message: "secondItem is defined but never used", line: 1, column: 25 }] }
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]
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});

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