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no-undefined.js 2.16 KiB
/**
 * @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); } } }; } };