Python-like string formatting for JavaScript.

format.js

Array.prototype.flatten = function() {
    return this.reduce(function(prev, cur) {
        var more = [].concat(cur).some(Array.isArray);
        return prev.concat(more ? cur.flatten() : cur);
    },[]);
};

String.prototype.format = function () {
    var content = this;
    // regular for loop would probably be more efficient than the forEach
    Array.prototype.slice.call(arguments).flatten().forEach(function (item, index) {
        var pattern = '\\{' + index + '\\}',
            re = new RegExp(pattern, "g");
        content = content.replace(re, item); 
    });
    return content;
};