sprintf

var sprintf = function (str) {
    var args = Array.prototype.slice.call(arguments, 1);
    return str.replace(/%0(\d+)d/g, function(m, num) {
        var r = String(args.shift());
        var c = '';
        num = parseInt(num) - r.length;
        while (--num >= 0) c += '0';
        return c + r;
    }).replace(/%[sdf]/g, function(m) { return sprintf._SPRINTF_HASH[m](args.shift()) });
};

sprintf._SPRINTF_HASH = {
    '%s': String,
    '%d': parseInt,
    '%f': parseFloat
};