/** * @fileoverview Rule to flag when initializing to undefined * @author Ilya Volodin */ "use strict"; const astUtils = require("./utils/ast-utils"); //------------------------------------------------------------------------------ // Rule Definition //------------------------------------------------------------------------------ /** @type {import('../types').Rule.RuleModule} */ module.exports = { meta: { type: "suggestion", docs: { description: "Disallow initializing variables to `undefined`", recommended: false, frozen: true, url: "https://eslint.org/docs/latest/rules/no-undef-init", }, schema: [], fixable: "code", messages: { unnecessaryUndefinedInit: "It's not necessary to initialize '{{name}}' to undefined.", }, }, create(context) { const sourceCode = context.sourceCode; return { VariableDeclarator(node) { const name = sourceCode.getText(node.id), init = node.init && node.init.name, scope = sourceCode.getScope(node), undefinedVar = astUtils.getVariableByName( scope, "undefined", ), shadowed = undefinedVar && undefinedVar.defs.length > 0, lastToken = sourceCode.getLastToken(node); if ( init === "undefined" && node.parent.kind !== "const" && !shadowed ) { context.report({ node, messageId: "unnecessaryUndefinedInit", data: { name }, fix(fixer) { if (node.parent.kind === "var") { return null; } if ( node.id.type === "ArrayPattern" || node.id.type === "ObjectPattern" ) { // Don't fix destructuring assignment to `undefined`. return null; } if ( sourceCode.commentsExistBetween( node.id, lastToken, ) ) { return null; } return fixer.removeRange([ node.id.range[1], node.range[1], ]); }, }); } }, }; }, };