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