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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: [],
-
- messages: {
- unexpectedUndefined: "Unexpected use of undefined."
- }
- },
-
- create(context) {
-
- /**
- * Report an invalid "undefined" identifier node.
- * @param {ASTNode} node The node to report.
- * @returns {void}
- */
- function report(node) {
- context.report({
- node,
- messageId: "unexpectedUndefined"
- });
- }
-
- /**
- * 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);
- }
- }
- };
-
- }
- };
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