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