Few JS functions

util-functions.js

/**
 * Extends `obj` with properties created as `key: value` for every pair of two consecutive arguments
 * @param  {Object} obj
 * @return {Object} obj
 */
function extendWithArgs(obj) {
	for (var i = 2; i < arguments.length; i += 2) {
		obj[arguments[i-1]] = arguments[i];
	}
	return obj;
}


/**
 * Creates an object as if using `new ctor()` but passing the arguments as an `Array` 
 * @param  {Function} ctor
 * @param  {Array} args
 * @return {Object} new object of constructor ctor
 */
function constructorApply(ctor, args) {
	var obj = Object.create(ctor.prototype);
	ctor.apply(obj, args);
	return obj;
}


/**
 * @method String.prototype.interpolate(...)
 * Interpolates a string.
 * @param {string...} arguments to interpolate
 * @returns {string}
 */
if (!String.prototype.interpolate) {
	Object.defineProperty(String.prototype, 'interpolate', {
		enumerable: false,
		value: function interpolate() {
			var args = arguments;
			return this.replace(/\{\d+\}/g, function(match) {
				return args[+match.slice(1, -1)];
			});
		}
	});
}