1 |
|
2 |
|
3 |
|
4 |
|
5 |
|
6 | "use strict";
|
7 |
|
8 |
|
9 |
|
10 |
|
11 |
|
12 | const astUtils = require("./utils/ast-utils");
|
13 |
|
14 |
|
15 |
|
16 |
|
17 |
|
18 |
|
19 |
|
20 |
|
21 |
|
22 |
|
23 | function isNaNIdentifier(node) {
|
24 | return Boolean(node) && node.type === "Identifier" && node.name === "NaN";
|
25 | }
|
26 |
|
27 |
|
28 |
|
29 |
|
30 |
|
31 | module.exports = {
|
32 | meta: {
|
33 | type: "problem",
|
34 |
|
35 | docs: {
|
36 | description: "require calls to `isNaN()` when checking for `NaN`",
|
37 | category: "Possible Errors",
|
38 | recommended: true,
|
39 | url: "https://eslint.org/docs/rules/use-isnan"
|
40 | },
|
41 |
|
42 | schema: [
|
43 | {
|
44 | type: "object",
|
45 | properties: {
|
46 | enforceForSwitchCase: {
|
47 | type: "boolean",
|
48 | default: true
|
49 | },
|
50 | enforceForIndexOf: {
|
51 | type: "boolean",
|
52 | default: false
|
53 | }
|
54 | },
|
55 | additionalProperties: false
|
56 | }
|
57 | ],
|
58 |
|
59 | messages: {
|
60 | comparisonWithNaN: "Use the isNaN function to compare with NaN.",
|
61 | switchNaN: "'switch(NaN)' can never match a case clause. Use Number.isNaN instead of the switch.",
|
62 | caseNaN: "'case NaN' can never match. Use Number.isNaN before the switch.",
|
63 | indexOfNaN: "Array prototype method '{{ methodName }}' cannot find NaN."
|
64 | }
|
65 | },
|
66 |
|
67 | create(context) {
|
68 |
|
69 | const enforceForSwitchCase = !context.options[0] || context.options[0].enforceForSwitchCase;
|
70 | const enforceForIndexOf = context.options[0] && context.options[0].enforceForIndexOf;
|
71 |
|
72 | |
73 |
|
74 |
|
75 |
|
76 |
|
77 | function checkBinaryExpression(node) {
|
78 | if (
|
79 | /^(?:[<>]|[!=]=)=?$/u.test(node.operator) &&
|
80 | (isNaNIdentifier(node.left) || isNaNIdentifier(node.right))
|
81 | ) {
|
82 | context.report({ node, messageId: "comparisonWithNaN" });
|
83 | }
|
84 | }
|
85 |
|
86 | /**
|
87 | * Checks the discriminant and all case clauses of the given `SwitchStatement` node for `switch(NaN)` and `case NaN:`
|
88 | * @param {ASTNode} node The node to check.
|
89 | * @returns {void}
|
90 | */
|
91 | function checkSwitchStatement(node) {
|
92 | if (isNaNIdentifier(node.discriminant)) {
|
93 | context.report({ node, messageId: "switchNaN" });
|
94 | }
|
95 |
|
96 | for (const switchCase of node.cases) {
|
97 | if (isNaNIdentifier(switchCase.test)) {
|
98 | context.report({ node: switchCase, messageId: "caseNaN" });
|
99 | }
|
100 | }
|
101 | }
|
102 |
|
103 | /**
|
104 | * Checks the given `CallExpression` node for `.indexOf(NaN)` and `.lastIndexOf(NaN)`.
|
105 | * @param {ASTNode} node The node to check.
|
106 | * @returns {void}
|
107 | */
|
108 | function checkCallExpression(node) {
|
109 | const callee = astUtils.skipChainExpression(node.callee);
|
110 |
|
111 | if (callee.type === "MemberExpression") {
|
112 | const methodName = astUtils.getStaticPropertyName(callee);
|
113 |
|
114 | if (
|
115 | (methodName === "indexOf" || methodName === "lastIndexOf") &&
|
116 | node.arguments.length === 1 &&
|
117 | isNaNIdentifier(node.arguments[0])
|
118 | ) {
|
119 | context.report({ node, messageId: "indexOfNaN", data: { methodName } });
|
120 | }
|
121 | }
|
122 | }
|
123 |
|
124 | const listeners = {
|
125 | BinaryExpression: checkBinaryExpression
|
126 | };
|
127 |
|
128 | if (enforceForSwitchCase) {
|
129 | listeners.SwitchStatement = checkSwitchStatement;
|
130 | }
|
131 |
|
132 | if (enforceForIndexOf) {
|
133 | listeners.CallExpression = checkCallExpression;
|
134 | }
|
135 |
|
136 | return listeners;
|
137 | }
|
138 | };
|
139 |
|
\ | No newline at end of file |