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The Number.isInteger() method determines whether the passed value is an integer.




The value to be tested for being an integer.

Return value

A Boolean indicating whether or not the given value is an integer.


If the target value is an integer, return true, otherwise return false. If the value is NaN or infinite, return false.


Number.isInteger(0);         // true
Number.isInteger(1);         // true
Number.isInteger(-100000);   // true

Number.isInteger(0.1);       // false
Number.isInteger(Math.PI);   // false

Number.isInteger(NaN);       // false
Number.isInteger(Infinity);  // false
Number.isInteger(-Infinity); // false
Number.isInteger('10');      // false
Number.isInteger(true);      // false
Number.isInteger(false);     // false
Number.isInteger([1]);       // false


Number.isInteger = Number.isInteger || function(value) {
  return typeof value === 'number' && 
    isFinite(value) && 
    Math.floor(value) === value;


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Number.isInteger' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Number.isInteger' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic Support(Yes)(Yes)16No(Yes)(Yes)
FeatureAndroidChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic Support(Yes)(Yes)(Yes)16No(Yes)(Yes)

See also

  • The Number object it belongs to.

Document Tags and Contributors

 Last updated by: fscholz,