Format numbers to a chosen number of decimal places in JavaScript

Description

The following code shows how to format numbers to a chosen number of decimal places.

Example


<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function formatNumber(theNum, numDecPlaces)
{<!--from   www.  java  2s .c om-->
var num = new String();
num = "" + theNum;
var pos = 0;
count = 0;
while (num.substring(pos-1,pos)!== ".") {
pos += 1 ;
count += 1;
}
while (pos < (count+numDecPlaces)){
pos +=1;
}
return num.substring(0,pos);
}

var entry;
var first;
var second;
var numPlaces;
first = Number(1);
second = Number(3);
numPlaces = Number(2);
var n = first / second;

document.write(n+"  vs  "+formatNumber(n,numPlaces));

</script>
</head>
<body>
</body>
</html>

Click to view the demo

The code above generates the following result.

Format numbers to a chosen number of decimal places in JavaScript

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