C# style string formatting in JavaScript

string.format.js

/**
 * C# style string formatting
 * 
 * @param {...string|...Number} args
 * @return {string}
 */
String.prototype.format = String.prototype.format || function() {
    return [].reduce.call(arguments, function(formatted, arg, i) {
        return formatted.replace('{' + i + '}', arg, 'gi');
    }, this);
};