noGlobalIsNan

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JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/suspicious/noGlobalIsNan
This rule is recommended, which means is enabled by default.
This rule has an unsafe fix.
The default severity of this rule is warning.

How to configure

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{
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  "linter": {
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    "rules": {
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      "suspicious": {
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        "noGlobalIsNan": "error"
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      }
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    }
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  }
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}

Description

Use Number.isNaN instead of global isNaN.

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.

Examples

Invalid

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isNaN({}); // true

code-block.js:1:1 lint/suspicious/noGlobalIsNan  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ isNaN is unsafe. It attempts a type coercion. Use Number.isNaN instead.
  
  > 1 │ isNaN({}); // true
      │ ^^^^^
    2 │ 
  
  ℹ See the MDN documentation for more details.
  
  ℹ Unsafe fix: Use Number.isNaN instead.
  
    1   │ - isNaN({});·//·true
      1 │ + Number.isNaN({});·//·true
    2 2 │

Valid

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Number.isNaN({}); // false