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
|
/**
* @fileoverview Rule to flag statements that use magic numbers (adapted from https://github.com/danielstjules/buddy.js)
* @author Vincent Lemeunier
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "disallow magic numbers",
category: "Best Practices",
recommended: false,
url: "https://eslint.org/docs/rules/no-magic-numbers"
},
schema: [{
type: "object",
properties: {
detectObjects: {
type: "boolean",
default: false
},
enforceConst: {
type: "boolean",
default: false
},
ignore: {
type: "array",
items: {
type: "number"
},
uniqueItems: true
},
ignoreArrayIndexes: {
type: "boolean",
default: false
}
},
additionalProperties: false
}],
messages: {
useConst: "Number constants declarations must use 'const'.",
noMagic: "No magic number: {{raw}}."
}
},
create(context) {
const config = context.options[0] || {},
detectObjects = !!config.detectObjects,
enforceConst = !!config.enforceConst,
ignore = config.ignore || [],
ignoreArrayIndexes = !!config.ignoreArrayIndexes;
/**
* Returns whether the node is number literal
* @param {Node} node - the node literal being evaluated
* @returns {boolean} true if the node is a number literal
*/
function isNumber(node) {
return typeof node.value === "number";
}
/**
* Returns whether the number should be ignored
* @param {number} num - the number
* @returns {boolean} true if the number should be ignored
*/
function shouldIgnoreNumber(num) {
return ignore.indexOf(num) !== -1;
}
/**
* Returns whether the number should be ignored when used as a radix within parseInt() or Number.parseInt()
* @param {ASTNode} parent - the non-"UnaryExpression" parent
* @param {ASTNode} node - the node literal being evaluated
* @returns {boolean} true if the number should be ignored
*/
function shouldIgnoreParseInt(parent, node) {
return parent.type === "CallExpression" && node === parent.arguments[1] &&
(parent.callee.name === "parseInt" ||
parent.callee.type === "MemberExpression" &&
parent.callee.object.name === "Number" &&
parent.callee.property.name === "parseInt");
}
/**
* Returns whether the number should be ignored when used to define a JSX prop
* @param {ASTNode} parent - the non-"UnaryExpression" parent
* @returns {boolean} true if the number should be ignored
*/
function shouldIgnoreJSXNumbers(parent) {
return parent.type.indexOf("JSX") === 0;
}
/**
* Returns whether the number should be ignored when used as an array index with enabled 'ignoreArrayIndexes' option.
* @param {ASTNode} parent - the non-"UnaryExpression" parent.
* @returns {boolean} true if the number should be ignored
*/
function shouldIgnoreArrayIndexes(parent) {
return parent.type === "MemberExpression" && ignoreArrayIndexes;
}
return {
Literal(node) {
const okTypes = detectObjects ? [] : ["ObjectExpression", "Property", "AssignmentExpression"];
if (!isNumber(node)) {
return;
}
let fullNumberNode;
let parent;
let value;
let raw;
// For negative magic numbers: update the value and parent node
if (node.parent.type === "UnaryExpression" && node.parent.operator === "-") {
fullNumberNode = node.parent;
parent = fullNumberNode.parent;
value = -node.value;
raw = `-${node.raw}`;
} else {
fullNumberNode = node;
parent = node.parent;
value = node.value;
raw = node.raw;
}
if (shouldIgnoreNumber(value) ||
shouldIgnoreParseInt(parent, fullNumberNode) ||
shouldIgnoreArrayIndexes(parent) ||
shouldIgnoreJSXNumbers(parent)) {
return;
}
if (parent.type === "VariableDeclarator") {
if (enforceConst && parent.parent.kind !== "const") {
context.report({
node: fullNumberNode,
messageId: "useConst"
});
}
} else if (
okTypes.indexOf(parent.type) === -1 ||
(parent.type === "AssignmentExpression" && parent.left.type === "Identifier")
) {
context.report({
node: fullNumberNode,
messageId: "noMagic",
data: {
raw
}
});
}
}
};
}
};
|
