What is isInteger() in Javascript?

isInteger() is a Number method that is used to determine if a given value is an integer. The isInteger() method is declared as follows:

Number.isInteger(value)
  • value: The value to be tested to check whether it is an integer or not.

Return value

The isInteger() method returns a boolean depending upon the value as follows:

  • The isInteger() method returns false if the value is not an integer.
  • The isInteger() method returns true if the value is an integer.

Browser compatibility

The isInteger() method is supported by the following browsers:

  • Edge 12
  • Firefox 16
  • Google Chrome 19
  • Opera 22
  • Safari 9

Note: The isInteger() method is not supported by Internet Explorer 11 and earlier versions.

Examples

Example 1

Consider the code snippet below, which demonstrates the use of the isInteger() method:

var foo = Number.isInteger(123)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(0)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(-123)
console.log("Given value is integer: ",foo);

Explanation

Positive, negative, and 0 integers are passed to the isInteger() method in line 1, line 4, and line 7, respectively. The isInteger() method returns true, as the given values are integers.

Example 2

Consider the code snippet below, in which non-integers are passed to the isInteger() method:

var foo = Number.isInteger("123") 
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(11.7)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(Infinity)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(NaN)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(true)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger(Math.PI)
console.log("Given value is integer: ",foo);
var foo = Number.isInteger([1])
console.log("Given value is integer: ",foo);

Explanation

Non-integers are passed to the isInteger() method in the code snippet above. The isInteger() method returns false for the non-integers.

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