JavaScript | Number.isInteger( ) function

The Number.isInteger() function in JavaScript is used to check whether the value passed to it is an integer or not. It returns true if the passed value is an integer, otherwise it return false.

Syntax:

Number.isInteger(value)

Parameters: This function accepts a single parameter value which specifies the number which the user wants to check for integer.

Return Value: The number.isInteger() function returns a boolean value ,i.e. either true or false. It will return true if the passed value is of the type Number and an integer, else it returns false.

Below examples illustrates the Number.isInteger() function in JavaScript:

  1. Passing a negative number as an argument: If a negative integer value is passed to the function as argument then the function will return true, if the negative value passed to it is not of integer type then the function will return false.

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    <script type="text/javascript">
        document.write(Number.isInteger(-2)); 
        document.write(Number.isInteger(-2.56));          
    </script>

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    Output:

    true
    false
    
  2. Passing a positive number as an argument: If a positive integer value is passed to the function as argument then the function will return true, if the positive value passed to it is not of integer type then the function will return false.

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    <script type="text/javascript">
        document.write(Number.isInteger(2));          
    </script>

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    Output:

    true
  3. Passing a zero as an argument: If zero is passed to the Number.isInteger() function then it will return true as zero is also an integer.

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    <script type="text/javascript">
        document.write(Number.isInteger(0));          
    </script>

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    Output:

    true
  4. Passing a number consisting of decimal places as an argument: If a decimal number is passed as argument, the function will return false.

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    <script type="text/javascript">
        document.write(Number.isInteger(2.03));          
    </script>

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    Output:

    false
  5. Passing a string as an argument: If the argument passed to the Number.isInteger() function is of type string then it will return false.

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    <script type="text/javascript">
        document.write("Output : " + Number.isInteger("hi"));          
    </script>

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    Output:

    false


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