John Clare - formatNumberString()

	John Clare's Personal Website	Sunday, May 20, 2012
	How many decimal places?

In any webApp development, there are a number of wheels re-invented over and over. This is one of those wheels - a way to force client-side numeric format, specific to a particular decimal precision. Go ahead and play with the following form.

Number:

Decimals:

The code hinges on one simple trick: integer rounding after multiplying the number by 10 to the [decimal] power, then dividing the number right back again - nice! Anyway, here's the javascript:

...and here's a direct link to just download the script file: numberString.js

function formatNumberString(value, decimals)

		{

		var str = (value == null) ? '0' : value.toString();

		str = str.replace(/^\s*|\s*$/g,"");

		str = (str.length == 0) ? '0' : str;

		var flt = (isNaN(str)) ? 0 : parseFloat(str);

		if (decimals == 0) return Math.round(flt).toString();

		var factor = Math.pow(10,decimals);

		flt = (Math.round(flt * factor)) / factor;

		var sides = flt.toString().split('.');

		var rside = (sides.length > 1) ? sides[1] : '0';

		for (var i=rside.length; i<decimals; i++)
		{rside += '0';}

		return sides[0] + '.' + rside.substr(0,decimals);

		}