no-undefined.js•2.29 kB
/**
* @fileoverview Rule to flag references to the undefined variable.
* @author Michael Ficarra
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "Disallow the use of `undefined` as an identifier",
recommended: false,
url: "https://eslint.org/docs/latest/rules/no-undefined"
},
schema: [],
messages: {
unexpectedUndefined: "Unexpected use of undefined."
}
},
create(context) {
const sourceCode = context.sourceCode;
/**
* 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"(node) {
const globalScope = sourceCode.getScope(node);
const stack = [globalScope];
while (stack.length) {
const scope = stack.pop();
stack.push(...scope.childScopes);
checkScope(scope);
}
}
};
}
};