Javascript sprintf()

sprintf.js

/**
 * sprintf()
 */
(function() {
	define(function() {
		
		return function() {
			
			var convert = function(match, nosign) {
				if (nosign) {
					match.sign = '';
				} else {
					match.sign = match.negative ? '-' : match.sign;
				}
				var l = match.min - match.argument.length + 1 - match.sign.length;
				var pad = new Array(l < 0 ? 0 : l).join(match.pad);
				if (!match.left) {
					if (match.pad == "0" || nosign) {
						return match.sign + pad + match.argument;
					} else {
						return pad + match.sign + match.argument;
					}
				} else {
					if (match.pad == "0" || nosign) {
						return match.sign + match.argument + pad.replace(/0/g, ' ');
					} else {
						return match.sign + match.argument + pad;
					}
				}
			};
			
			if (typeof arguments == "undefined") { return null; }
			if (arguments.length < 1) { return null; }
			if (typeof arguments[0] != "string") { return null; }
			if (typeof RegExp == "undefined") { return null; }
			
			var string = arguments[0];
			var exp = new RegExp(/(%([%]|(\-)?(\+|\x20)?(0)?(\d+)?(\.(\d)?)?([bcdfosxX])))/g);
			var matches = new Array();
			var strings = new Array();
			var convCount = 0;
			var stringPosStart = 0;
			var stringPosEnd = 0;
			var matchPosEnd = 0;
			var newString = '';
			var match = null;
			
			while (match = exp.exec(string)) {
				
				if (match[9]) { convCount += 1; }
				
				stringPosStart = matchPosEnd;
				stringPosEnd = exp.lastIndex - match[0].length;
				strings[strings.length] = string.substring(stringPosStart, stringPosEnd);
				
				matchPosEnd = exp.lastIndex;
				matches[matches.length] = {
					match: match[0],
					left: match[3] ? true : false,
					sign: match[4] || '',
					pad: match[5] || ' ',
					min: match[6] || 0,
					precision: match[8],
					code: match[9] || '%',
					negative: parseInt(arguments[convCount]) < 0 ? true : false,
					argument: String(arguments[convCount])
				};
			}
			strings[strings.length] = string.substring(matchPosEnd);
			
			if (matches.length == 0) { return string; }
			if ((arguments.length - 1) < convCount) { return null; }
			
			var code = null;
			var match = null;
			var i = null;
			
			for (i = 0; i < matches.length; i++) {
				
				if (matches[i].code == '%') { substitution = '%' }
				else if (matches[i].code == 'b') {
					matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(2));
					substitution = convert(matches[i], true);
				} else if (matches[i].code == 'c') {
					matches[i].argument = String(String.fromCharCode(parseInt(Math.abs(parseInt(matches[i].argument)))));
					substitution = convert(matches[i], true);
				} else if (matches[i].code == 'd') {
					matches[i].argument = String(Math.abs(parseInt(matches[i].argument)));
					substitution = convert(matches[i]);
				} else if (matches[i].code == 'f') {
					matches[i].argument = String(Math.abs(parseFloat(matches[i].argument)).toFixed(matches[i].precision ? matches[i].precision : 6));
					substitution = convert(matches[i]);
				} else if (matches[i].code == 'o') {
					matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(8));
					substitution = convert(matches[i]);
				} else if (matches[i].code == 's') {
					matches[i].argument = matches[i].argument.substring(0, matches[i].precision ? matches[i].precision : matches[i].argument.length)
					substitution = convert(matches[i], true);
				} else if (matches[i].code == 'x') {
					matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(16));
					substitution = convert(matches[i]);
				} else if (matches[i].code == 'X') {
					matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(16));
					substitution = convert(matches[i]).toUpperCase();
				} else {
					substitution = matches[i].match;
				}
				
				newString += strings[i];
				newString += substitution;
				
			}
			newString += strings[i];
			
			return newString;
		};
	});
})();