useIsNan

JavaScript (and super languages)

摘要

¥Summary

规则生效日期：v1.0.0

¥Rule available since: v1.0.0
诊断类别：lint/correctness/useIsNan

¥Diagnostic Category: lint/correctness/useIsNan
此规则为推荐规则，默认启用。

¥This rule is recommended, which means is enabled by default.
此规则包含 unsafe 修复程序。

¥This rule has an unsafe fix.
此规则的默认严重级别为 error。

¥The default severity of this rule is error.
来源：

¥Sources:
- 与 use-isnan 相同
  
  ¥Same as use-isnan

如何配置

¥How to configure

1
{
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  "linter": {
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    "rules": {
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      "correctness": {
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        "useIsNan": "error"
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      }
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    }
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  }
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}

描述

¥Description

要求在检查 NaN 时调用 isNaN()。

¥Require calls to isNaN() when checking for NaN.

在 JavaScript 中，NaN 是 Number 类型的特殊值。它用于表示由 IEEE 二进制浮点算术标准指定的双精度 64 位格式表示的任何 “not-a-number” 值。

¥In JavaScript, NaN is a special value of the Number type. It’s used to represent any of the “not-a-number” values represented by the double-precision 64-bit format as specified by the IEEE Standard for Binary Floating-Point Arithmetic.

因为 NaN 在 JavaScript 中是唯一的，不等于任何东西，包括它自己，所以与 NaN 的比较结果令人困惑：

¥Because NaN is unique in JavaScript by not being equal to anything, including itself, the results of comparisons to NaN are confusing:

NaN === NaN 或 NaN == NaN 计算结果为 false

¥NaN === NaN or NaN == NaN evaluate to false
NaN !== NaN 或 NaN != NaN 计算结果为 true

¥NaN !== NaN or NaN != NaN evaluate to true

因此，使用 Number.isNaN() 或全局 isNaN() 函数来测试值是否为 NaN。

¥Therefore, use Number.isNaN() or global isNaN() functions to test whether a value is NaN.

请注意 Number.isNaN() 和 isNaN() 没有相同的行为。当 isNaN() 的参数不是数字时，首先将值强制转换为数字。Number.isNaN() 不执行此强制。因此，这是一种更可靠的方法来测试值是否为 NaN。

¥Note that Number.isNaN() and isNaN() do not have the same behavior. When the argument to isNaN() is not a number, the value is first coerced to a number. Number.isNaN() does not perform this coercion. Therefore, it is a more reliable way to test whether a value is NaN.

示例

¥Examples

无效

¥Invalid

1
123 == NaN

code-block.js:1:1 lint/correctness/useIsNan  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Use the Number.isNaN function to compare with NaN.
  
  > 1 │ 123 == NaN
      │ ^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use Number.isNaN() instead.
  
    1   │ - 123·==·NaN
      1 │ + Number.isNaN(123)
    2 2 │

1
123 != NaN

code-block.js:1:1 lint/correctness/useIsNan  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Use the Number.isNaN function to compare with NaN.
  
  > 1 │ 123 != NaN
      │ ^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use Number.isNaN() instead.
  
    1   │ - 123·!=·NaN
      1 │ + !Number.isNaN(123)
    2 2 │

1
switch(foo) { case (NaN): break; }

code-block.js:1:20 lint/correctness/useIsNan ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ ‘case NaN’ can never match. Use Number.isNaN before the switch.
  
  > 1 │ switch(foo) { case (NaN): break; }
      │                    ^^^^^
    2 │

1
Number.NaN == "abc"

code-block.js:1:1 lint/correctness/useIsNan  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Use the Number.isNaN function to compare with NaN.
  
  > 1 │ Number.NaN == “abc”
      │ ^^^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use Number.isNaN() instead.
  
    1   │ - Number.NaN·==·“abc”
      1 │ + Number.isNaN(“abc”)
    2 2 │

有效

¥Valid

1
if (Number.isNaN(123) !== true) {}
2

3
foo(Number.NaN / 2)
4

5
switch(foo) {}

useIsNan

摘要

如何配置

描述

示例

无效

有效

相关链接