forked from eslint/eslint
-
Notifications
You must be signed in to change notification settings - Fork 0
/
use-isnan.js
168 lines (143 loc) · 5.87 KB
/
use-isnan.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
/**
* @fileoverview Rule to flag comparisons to the value NaN
* @author James Allardice
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Determines if the given node is a NaN `Identifier` node.
* @param {ASTNode|null} node The node to check.
* @returns {boolean} `true` if the node is 'NaN' identifier.
*/
function isNaNIdentifier(node) {
return Boolean(node) && (
astUtils.isSpecificId(node, "NaN") ||
astUtils.isSpecificMemberAccess(node, "Number", "NaN")
);
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
hasSuggestions: true,
type: "problem",
docs: {
description: "Require calls to `isNaN()` when checking for `NaN`",
recommended: true,
url: "https://eslint.org/docs/latest/rules/use-isnan"
},
schema: [
{
type: "object",
properties: {
enforceForSwitchCase: {
type: "boolean",
default: true
},
enforceForIndexOf: {
type: "boolean",
default: false
}
},
additionalProperties: false
}
],
messages: {
comparisonWithNaN: "Use the isNaN function to compare with NaN.",
switchNaN: "'switch(NaN)' can never match a case clause. Use Number.isNaN instead of the switch.",
caseNaN: "'case NaN' can never match. Use Number.isNaN before the switch.",
indexOfNaN: "Array prototype method '{{ methodName }}' cannot find NaN.",
replaceWithIsNaN: "Replace with Number.isNaN."
}
},
create(context) {
const enforceForSwitchCase = !context.options[0] || context.options[0].enforceForSwitchCase;
const enforceForIndexOf = context.options[0] && context.options[0].enforceForIndexOf;
const sourceCode = context.getSourceCode();
const fixableOperators = new Set(["==", "===", "!=", "!=="]);
/**
* Checks the given `BinaryExpression` node for `foo === NaN` and other comparisons.
* @param {ASTNode} node The node to check.
* @returns {void}
*/
function checkBinaryExpression(node) {
if (
/^(?:[<>]|[!=]=)=?$/u.test(node.operator) &&
(isNaNIdentifier(node.left) || isNaNIdentifier(node.right))
) {
const isFixable = fixableOperators.has(node.operator);
if (isFixable) {
context.report({
node,
messageId: "comparisonWithNaN",
suggest: [
{
messageId: "replaceWithIsNaN",
fix(fixer) {
const comparedValue = isNaNIdentifier(node.left) ? node.right : node.left;
const shouldNegate = node.operator[0] === "!";
const negation = shouldNegate ? "!" : "";
const comparedValueText = sourceCode.getText(comparedValue);
return fixer.replaceText(node, `${negation}Number.isNaN(${comparedValueText})`);
}
}
]
});
} else {
context.report({ node, messageId: "comparisonWithNaN" });
}
}
}
/**
* Checks the discriminant and all case clauses of the given `SwitchStatement` node for `switch(NaN)` and `case NaN:`
* @param {ASTNode} node The node to check.
* @returns {void}
*/
function checkSwitchStatement(node) {
if (isNaNIdentifier(node.discriminant)) {
context.report({ node, messageId: "switchNaN" });
}
for (const switchCase of node.cases) {
if (isNaNIdentifier(switchCase.test)) {
context.report({ node: switchCase, messageId: "caseNaN" });
}
}
}
/**
* Checks the given `CallExpression` node for `.indexOf(NaN)` and `.lastIndexOf(NaN)`.
* @param {ASTNode} node The node to check.
* @returns {void}
*/
function checkCallExpression(node) {
const callee = astUtils.skipChainExpression(node.callee);
if (callee.type === "MemberExpression") {
const methodName = astUtils.getStaticPropertyName(callee);
if (
(methodName === "indexOf" || methodName === "lastIndexOf") &&
node.arguments.length === 1 &&
isNaNIdentifier(node.arguments[0])
) {
context.report({ node, messageId: "indexOfNaN", data: { methodName } });
}
}
}
const listeners = {
BinaryExpression: checkBinaryExpression
};
if (enforceForSwitchCase) {
listeners.SwitchStatement = checkSwitchStatement;
}
if (enforceForIndexOf) {
listeners.CallExpression = checkCallExpression;
}
return listeners;
}
};