printf

printf.js

// courtesy of http://www.reddit.com/user/itsnotlupus @
// http://bit.ly/upcWxw
function printf(msg) {       
    var args = Array.prototype.slice.call(arguments,1), arg;
    return msg.replace(/(%[disv])/g, function(a,val) { 
        arg = args.shift();
        if (arg !== undefined) {
            switch(val.charCodeAt(1)){
                case 100: return +arg; // d
                case 105: return Math.round(+arg); // i
                case 115: return String(arg); // s
                case 118: return arg; // v
            }
        }
        return val;
    });
}

// console.log( printf("I have %d cats, 2 %s, and %i bird. %v", -3, "dogs", 1.43, window) );