format.js

/**
 * Does the same as a simple form of python "".format
 * that will not work for anything else than number or string.
 * Array form :
 *      "I have {} replacements to {}".format("two", "make")
 *      "I have {} replacements to {}".format(["two", "make"])
 *      "I have {0} replacements to {1}".format(["two", "make"])
 * Dict form :
 *      "Hello {name} !".format({name: "Bob"});
 *      "I am {age} years old".format({age: 12});
 *      "Pi is {pi} ! ".format({"pi": Math.PI});
 * No error is outputted in case of malformed input. It just isn't replaced.
 **/
String.prototype.format = function (obj) {

	var source = (typeof obj === 'object') ? obj : arguments,
		i = 0
	;
	return this.replace(/{([^{}]*)}/g, function (a, b) {
			
		if (b === "") {
			b = i++;
		}
		
		var r = source[b];
		return (typeof r === 'string' || typeof r === 'number') ? r : a;
	});
};