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]

JS Number

  1. Format Number
  2. String to Number
  3. Number Object
  4. Number.prototype

JS String

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  2. Template String
  3. Char, Code Unit, Codepoint
  4. String Escape Sequence
  5. Unicode Escape Sequence
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