JS: Number.isNaN

By Xah Lee. Date: . Last updated: .

Number.isNaN ( number )

If number is NaN, return true, else false.

(NaN is a primitive value of number type that represents “not a number”.)

[see JS: NaN]

console.log ( Number.isNaN ( NaN ) ); // true

console.log ( Number.isNaN ( "NaN" ) ); // false
console.log ( Number.isNaN ( "3" ) ); // false
console.log ( Number.isNaN ( 3 ) ); // false
console.log ( Number.isNaN ( Infinity ) ); // false

Number.isNaN and the global isNaN are different.

isNaN converts argument to number first. Number.isNaN does not.

[see JS: isNaN]

Reference

ECMAScript® 2016 Language Specification#sec-number.isnan

Number Topic

  1. JS: Format Number
  2. JS: String to Number
  3. JS: Number Object
  4. JS: Number Constructor
  5. JS: Number.prototype

JS String

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  3. Char, Code Unit, Code Point
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  6. String to Number
  7. Encode URL, Escape String
  8. Format Number
  9. Source Code Encoding
  10. Allowed Characters in Identifier
  11. String Object
  12. String.prototype
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