Javascript Reference - JavaScript Number() Function

The Number() function converts the object argument to a number that represents the object's value.

If the value cannot be converted to a legal number, NaN is returned.


var firstVal = "5";
var secondVal = "5";
var result = Number(firstVal) + Number(secondVal);
console.log("Result: " + result);
/* ww  w .  j av a  2  s. c  o m*/
var num = Number("+1.1")
console.log(num);

num = Number("-1.1")
console.log(num);

num = Number("+123")
console.log(num);

num = Number("asdf")
console.log(num);

num = Number("0123")
console.log(num);

num = Number("0xf")
console.log(num);

num = Number("-0xf")
console.log(num);

num = Number("01.1")
console.log(num);

num = Number(null)
console.log(num);

num = Number(false)
console.log(num);

num = Number("")
console.log(num);

num = Number(undefined)
console.log(num);

The code above generates the following result.

Browser Support


`Number`	Yes	Yes	Yes	Yes	Yes

Syntax

Number(object)

Parameter Values

Parameter	Description
object	Optional. A JavaScript object. If no argument is provided, it returns 0.

Return Value

It return a number by converting object to numbers. If the value cannot be converted to a legal number, NaN is returned. If no argument is provided, it returns 0.

Example

The following code shows how to convert different object values to their numbers.


<!DOCTYPE html>
<html>
<body>
<button onclick="myFunction()">test</button>
<p id="demo"></p>
<script>
function myFunction() {<!--from www  .j  ava2 s.c o m-->
    var x1 = true;
    var x2 = false;
    var x3 = new Date();
    var x4 = "9 9";
    var x5 = "999 888";

    var n = 
    Number(x1) + "<br>" + 
    Number(x2) + "<br>" + 
    Number(x3) + "<br>" + 
    Number(x4) + "<br>" + 
    Number(x5);
    document.getElementById("demo").innerHTML = n;
}
</script>

</body>
</html>

The code above is rendered as follows: