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| /** | |
| * @fileoverview Rule to flag references to the undefined variable. | |
| * @author Michael Ficarra | |
| */ | |
| "use strict"; | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
| module.exports = { | |
| meta: { | |
| type: "suggestion", | |
| docs: { | |
| description: "disallow the use of `undefined` as an identifier", | |
| category: "Variables", | |
| recommended: false, | |
| url: "https://eslint.org/docs/rules/no-undefined" | |
| }, | |
| schema: [] | |
| }, | |
| create(context) { | |
| /** | |
| * Report an invalid "undefined" identifier node. | |
| * @param {ASTNode} node The node to report. | |
| * @returns {void} | |
| */ | |
| function report(node) { | |
| context.report({ | |
| node, | |
| message: "Unexpected use of undefined." | |
| }); | |
| } | |
| /** | |
| * Checks the given scope for references to `undefined` and reports | |
| * all references found. | |
| * @param {eslint-scope.Scope} scope The scope to check. | |
| * @returns {void} | |
| */ | |
| function checkScope(scope) { | |
| const undefinedVar = scope.set.get("undefined"); | |
| if (!undefinedVar) { | |
| return; | |
| } | |
| const references = undefinedVar.references; | |
| const defs = undefinedVar.defs; | |
| // Report non-initializing references (those are covered in defs below) | |
| references | |
| .filter(ref => !ref.init) | |
| .forEach(ref => report(ref.identifier)); | |
| defs.forEach(def => report(def.name)); | |
| } | |
| return { | |
| "Program:exit"() { | |
| const globalScope = context.getScope(); | |
| const stack = [globalScope]; | |
| while (stack.length) { | |
| const scope = stack.pop(); | |
| stack.push(...scope.childScopes); | |
| checkScope(scope); | |
| } | |
| } | |
| }; | |
| } | |
| }; |