JavaScript - isInteger() method

revision:

Category : number

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

Syntax : 

        Number.isInteger(value)

Parameters:

value : required.The value to be tested for being an integer.

Examples:

        function fits(x, y) {
            if (Number.isInteger(y / x)) {
              return 'Fits!';
            }
            return 'Does NOT fit!';
        }
        console.log(fits(5, 10));
          // Expected output: "Fits!"
        console.log(fits(5, 11));
          // Expected output: "Does NOT fit!"

Practical examples

example: using isInteger() method.

code: 
                    <div>
                        <p id="integer-1"></p>
                        <p id="integer-2"></p>
                        <p id="integer-3"></p>
                        <p id="integer-4"></p>
                        <p id="integer-5"></p>
                        <p id="integer-6"></p>
                        <p id="integer-7"></p>
                        <p id="integer-8"></p>
                        <p id="integer-9"></p>
                        <p id="integer-10"></p>
                        <p id="integer-11"></p>
                        <p id="integer-12"></p>
                        <p id="integer-13"></p>
                        <p id="integer-14"></p>
                        <p id="integer-15"></p>
                        <p id="integer-16"></p>
                        <p id="integer-17"></p>
            
                    </div>
                    <script>
                        document.getElementById("integer-1").innerHTML = "Number.isInteger(0) : " + Number.isInteger(0); // true
                        document.getElementById("integer-2").innerHTML = "Number.isInteger(1) : " + Number.isInteger(1); // true
                        document.getElementById("integer-3").innerHTML = "Number.isInteger(-100000) : " + Number.isInteger(-100000); // true
                        document.getElementById("integer-4").innerHTML = "Number.isInteger(99999999999999999999999) : " 
                        + Number.isInteger(99999999999999999999999); // true
                        document.getElementById("integer-5").innerHTML = "Number.isInteger(0.1) : " + Number.isInteger(0.1); // false
                        document.getElementById("integer-6").innerHTML = "Number.isInteger(Math.Pi) : " + Number.isInteger(Math.PI); // false
                        document.getElementById("integer-7").innerHTML = "Number.isInteger(NaN) : " + Number.isInteger(NaN); // false
                        document.getElementById("integer-8").innerHTML = "Number.isInteger(Infinity) : " + Number.isInteger(Infinity); // false
                        document.getElementById("integer-9").innerHTML = "Number.isInteger(-Infinity) : " + Number.isInteger(-Infinity); // false
                        document.getElementById("integer-10").innerHTML = "Number.isInteger('10') : " + Number.isInteger('10'); // false
                        document.getElementById("integer-11").innerHTML = "Number.isInteger(true) : " + Number.isInteger(true); // false
                        document.getElementById("integer-12").innerHTML = "Number.isInteger(false) : " + Number.isInteger(false); // false
                        document.getElementById("integer-13").innerHTML = "Number.isInteger([1]) : " + Number.isInteger([1]); // false
                        document.getElementById("integer-14").innerHTML = "Number.isInteger(5.0) : " + Number.isInteger(5.0); // false
                        document.getElementById("integer-15").innerHTML = "Number.isInteger(5.000000000000001) : "
                        + Number.isInteger(5.000000000000001); // false
                        document.getElementById("integer-16").innerHTML = "Number.isInteger(5.0000000000000001) : " 
                        + Number.isInteger(5.0000000000000001); // true, because of loss of precision
                        document.getElementById("integer-17").innerHTML = "Number.isInteger(4500000000000000.1) : " 
                        + Number.isInteger(4500000000000000.1); // true, because of loss of precision
            
                    </script>