noGlobalIsNan

Diagnostic Category: lint/suspicious/noGlobalIsNan

JavaScript (and super languages)

Since: v1.0.0

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

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

Number.isNaN({}); // false

How to configure

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