[d565449] | 1 | /**
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| 2 | * @fileoverview Rule to
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| 3 | * @author Toru Nagashima
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| 4 | */
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| 5 |
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| 6 | "use strict";
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| 7 |
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| 8 | //------------------------------------------------------------------------------
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| 9 | // Helpers
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| 10 | //------------------------------------------------------------------------------
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| 11 |
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| 12 | /**
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| 13 | * Gets the variable object of `arguments` which is defined implicitly.
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| 14 | * @param {eslint-scope.Scope} scope A scope to get.
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| 15 | * @returns {eslint-scope.Variable} The found variable object.
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| 16 | */
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| 17 | function getVariableOfArguments(scope) {
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| 18 | const variables = scope.variables;
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| 19 |
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| 20 | for (let i = 0; i < variables.length; ++i) {
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| 21 | const variable = variables[i];
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| 22 |
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| 23 | if (variable.name === "arguments") {
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| 24 |
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| 25 | /*
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| 26 | * If there was a parameter which is named "arguments", the implicit "arguments" is not defined.
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| 27 | * So does fast return with null.
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| 28 | */
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| 29 | return (variable.identifiers.length === 0) ? variable : null;
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| 30 | }
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| 31 | }
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| 32 |
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| 33 | /* c8 ignore next */
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| 34 | return null;
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| 35 | }
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| 36 |
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| 37 | /**
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| 38 | * Checks if the given reference is not normal member access.
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| 39 | *
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| 40 | * - arguments .... true // not member access
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| 41 | * - arguments[i] .... true // computed member access
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| 42 | * - arguments[0] .... true // computed member access
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| 43 | * - arguments.length .... false // normal member access
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| 44 | * @param {eslint-scope.Reference} reference The reference to check.
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| 45 | * @returns {boolean} `true` if the reference is not normal member access.
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| 46 | */
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| 47 | function isNotNormalMemberAccess(reference) {
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| 48 | const id = reference.identifier;
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| 49 | const parent = id.parent;
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| 50 |
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| 51 | return !(
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| 52 | parent.type === "MemberExpression" &&
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| 53 | parent.object === id &&
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| 54 | !parent.computed
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| 55 | );
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| 56 | }
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| 57 |
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| 58 | //------------------------------------------------------------------------------
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| 59 | // Rule Definition
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| 60 | //------------------------------------------------------------------------------
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| 61 |
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| 62 | /** @type {import('../shared/types').Rule} */
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| 63 | module.exports = {
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| 64 | meta: {
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| 65 | type: "suggestion",
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| 66 |
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| 67 | docs: {
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| 68 | description: "Require rest parameters instead of `arguments`",
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| 69 | recommended: false,
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| 70 | url: "https://eslint.org/docs/latest/rules/prefer-rest-params"
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| 71 | },
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| 72 |
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| 73 | schema: [],
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| 74 |
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| 75 | messages: {
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| 76 | preferRestParams: "Use the rest parameters instead of 'arguments'."
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| 77 | }
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| 78 | },
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| 79 |
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| 80 | create(context) {
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| 81 |
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| 82 | const sourceCode = context.sourceCode;
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| 83 |
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| 84 | /**
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| 85 | * Reports a given reference.
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| 86 | * @param {eslint-scope.Reference} reference A reference to report.
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| 87 | * @returns {void}
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| 88 | */
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| 89 | function report(reference) {
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| 90 | context.report({
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| 91 | node: reference.identifier,
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| 92 | loc: reference.identifier.loc,
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| 93 | messageId: "preferRestParams"
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| 94 | });
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| 95 | }
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| 96 |
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| 97 | /**
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| 98 | * Reports references of the implicit `arguments` variable if exist.
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| 99 | * @param {ASTNode} node The node representing the function.
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| 100 | * @returns {void}
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| 101 | */
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| 102 | function checkForArguments(node) {
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| 103 | const argumentsVar = getVariableOfArguments(sourceCode.getScope(node));
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| 104 |
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| 105 | if (argumentsVar) {
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| 106 | argumentsVar
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| 107 | .references
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| 108 | .filter(isNotNormalMemberAccess)
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| 109 | .forEach(report);
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| 110 | }
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| 111 | }
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| 112 |
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| 113 | return {
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| 114 | "FunctionDeclaration:exit": checkForArguments,
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| 115 | "FunctionExpression:exit": checkForArguments
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| 116 | };
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| 117 | }
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| 118 | };
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