Number.isFinite()

Why Number.isFinite ?

The Number.isFinite () method checks whether the specified value is finite. Returns “true” if the value to be checked is finite. Returns false if the value to be checked is not finite. Number.isFinite () does not convert values to a Number and does not return true for any value that is not of Number.

The Number.isfinite () method differs from the isfinite () function because this method does not force the parameter to a number and does not return true for any value that does not have a type number. Number.isFinite () is different from global isFinite (). The global isFinite () function converts the tested value to a Number, then tests it.

Syntax:

Number.isFinite(value)

• value (required): The value to be tested.

---

JavaScript Number.isFinite Examples

Example 1

        let val1 = Number.isFinite(1234);
        let val2 = Number.isFinite(1.55);
        let val3 = Number.isFinite(-8.99);
        let val4 = Number.isFinite(0);
        let val5 = Number.isFinite(null);
        let val6 = Number.isFinite("394");
        let val7 = Number.isFinite("truecodes.org");
        let val8 = Number.isFinite(2000/1000);
        let val9 = Number.isFinite(Infinity);
        let val10 = Number.isFinite(-Infinity);
        let val11 = Number.isFinite(0 / 0);
        let val12 = Number.isFinite(function(){});
        let val13 = Number.isFinite(2019 / 02 / 03);

        console.log(val1);
        console.log(val2);
        console.log(val3);
        console.log(val4);
        console.log(val5);
        console.log(val6);
        console.log(val7);
        console.log(val8);
        console.log(val9);
        console.log(val10);
        console.log(val11);
        console.log(val12);
        console.log(val13);

output:

true
true
true
true
false
false
false
true
false
false
false
false
true

---

Example 2

        function div(x) {
            if (Number.isFinite(1000 / x)) {
                return 'Number is NOT Infinity.';
            }
            return 'Number is Infinity!';
        }

        console.log(div(0));

        console.log(div(1));

output:

Number is Infinity!
Number is NOT Infinity.

---

Polyfill

if (Number.isFinite === undefined) Number.isFinite = function(value) {
    return typeof value === 'number' && isFinite(value);
}

---

Source:

• https://developer.mozilla.org

---

Browser Support

Chrome	19
Edge	yes
Firefox	16
Internet Explorer	no
Opera	15
Safari	9
Android webview	yes
Chrome for Android	yes
Edge mobile	yes
Firefox for Android	16
Opera Android	yes