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/**
* @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],
]);
},
});
}
},
};
},
};
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