128 lines
4.9 KiB
Plaintext
128 lines
4.9 KiB
Plaintext
/**
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* @fileoverview Ensures that the results of typeof are compared against a valid string
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* @author Ian Christian Myers
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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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: "problem",
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docs: {
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description: "Enforce comparing `typeof` expressions against valid strings",
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recommended: true,
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url: "https://eslint.org/docs/latest/rules/valid-typeof"
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},
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hasSuggestions: true,
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schema: [
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{
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type: "object",
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properties: {
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requireStringLiterals: {
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type: "boolean",
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default: false
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}
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},
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additionalProperties: false
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}
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],
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messages: {
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invalidValue: "Invalid typeof comparison value.",
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notString: "Typeof comparisons should be to string literals.",
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suggestString: 'Use `"{{type}}"` instead of `{{type}}`.'
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}
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},
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create(context) {
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const VALID_TYPES = new Set(["symbol", "undefined", "object", "boolean", "number", "string", "function", "bigint"]),
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OPERATORS = new Set(["==", "===", "!=", "!=="]);
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const sourceCode = context.sourceCode;
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const requireStringLiterals = context.options[0] && context.options[0].requireStringLiterals;
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let globalScope;
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/**
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* Checks whether the given node represents a reference to a global variable that is not declared in the source code.
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* These identifiers will be allowed, as it is assumed that user has no control over the names of external global variables.
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* @param {ASTNode} node `Identifier` node to check.
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* @returns {boolean} `true` if the node is a reference to a global variable.
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*/
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function isReferenceToGlobalVariable(node) {
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const variable = globalScope.set.get(node.name);
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return variable && variable.defs.length === 0 &&
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variable.references.some(ref => ref.identifier === node);
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}
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/**
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* Determines whether a node is a typeof expression.
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* @param {ASTNode} node The node
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* @returns {boolean} `true` if the node is a typeof expression
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*/
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function isTypeofExpression(node) {
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return node.type === "UnaryExpression" && node.operator === "typeof";
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}
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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Program(node) {
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globalScope = sourceCode.getScope(node);
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},
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UnaryExpression(node) {
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if (isTypeofExpression(node)) {
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const { parent } = node;
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if (parent.type === "BinaryExpression" && OPERATORS.has(parent.operator)) {
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const sibling = parent.left === node ? parent.right : parent.left;
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if (sibling.type === "Literal" || astUtils.isStaticTemplateLiteral(sibling)) {
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const value = sibling.type === "Literal" ? sibling.value : sibling.quasis[0].value.cooked;
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if (!VALID_TYPES.has(value)) {
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context.report({ node: sibling, messageId: "invalidValue" });
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}
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} else if (sibling.type === "Identifier" && sibling.name === "undefined" && isReferenceToGlobalVariable(sibling)) {
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context.report({
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node: sibling,
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messageId: requireStringLiterals ? "notString" : "invalidValue",
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suggest: [
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{
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messageId: "suggestString",
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data: { type: "undefined" },
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fix(fixer) {
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return fixer.replaceText(sibling, '"undefined"');
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}
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}
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]
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});
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} else if (requireStringLiterals && !isTypeofExpression(sibling)) {
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context.report({ node: sibling, messageId: "notString" });
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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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