decimal expansion function

decimalExpansion.js

// borrowed from jQuery 1.7.2
var isNumeric = function(val){
	return !isNaN(parseFloat(val)) && isFinite(val);
};
/**
* @author Larry Battle <http://bateru.com/news/contact-me>
* @date May 16, 2012
* @license MIT and GPLv3
*/
//decimalExpansion returns a string representation of a divided by b to a fixed length.
// All the paramaters must be whole numbers.
// Example: decimalExpansion( 1, 3, 3 ) === "0.333"
var decimalExpansion = function (top, bottom, decLength) {
	if (!isNumeric(top) || !isNumeric(bottom) || !isNumeric(decLength) || !bottom) {
		return null;
	}
	var sign = ((top * bottom) != Math.abs(top * bottom)) ? "-" : "";
	top = Math.abs(top);
	bottom = Math.abs(bottom);
	decLength = Math.abs(decLength);
 
	var result = Math.floor(top / bottom),
	remainder = top % bottom,
	maxDecimal = 100,
	i = Math.min(Math.max(0, decLength), maxDecimal) + 1;
 
	if (1 < i) {
		result += ".";
		while (i--) {
			top = remainder * 10;
			remainder = top % bottom;
			result += "" + Math.floor(top / bottom);
		}
		result = result.replace(/(\d)(\d)$/, function (match, a, b) {
				return +b > 4 ? +a + 1 : a;
			});
	}
	return sign + result;
};