Decimal round Javascript

gistfile1.txt

// Closure
		(function(){

			/**
			 * Decimal adjustment of a number.
			 *
			 * @param	{String}	type	The type of adjustment.
			 * @param	{Number}	value	The number.
			 * @param	{Integer}	exp		The exponent (the 10 logarithm of the adjustment base).
			 * @returns	{Number}			The adjusted value.
			 */
			function decimalAdjust(type, value, exp) {
				// If the exp is undefined or zero...
				if (typeof exp === 'undefined' || +exp === 0) {
					return Math[type](value);
				}
				value = +value;
				exp = +exp;
				// If the value is not a number or the exp is not an integer...
				if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) {
					return NaN;
				}
				// Shift
				value = value.toString().split('e');
				value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp)));
				// Shift back
				value = value.toString().split('e');
				return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp));
			}

			// Decimal round
			if (!Math.round10) {
				Math.round10 = function(value, exp) {
					return decimalAdjust('round', value, exp);
				};
			}
			// Decimal floor
			if (!Math.floor10) {
				Math.floor10 = function(value, exp) {
					return decimalAdjust('floor', value, exp);
				};
			}
			// Decimal ceil
			if (!Math.ceil10) {
				Math.ceil10 = function(value, exp) {
					return decimalAdjust('ceil', value, exp);
				};
			}

		})();