JavaScript: Multiplication for String

StringMul1.js

/* a clever way to implement string multiplication in JavaScript */
String.prototype.times = function(n) {
    return Array.prototype.join.call({length:n+1}, this);
};
"js".times(5) // => "jsjsjsjsjs"

StringMul2.js

/* a simpler version that might be just as efficient */
String.prototype.times = function(n) {
    return (new Array(n+1)).join(this);
};

StringMul3.js

/* based on string doubling by recursion */
String.prototype.times = function(n) {
    if ( n == 1 ) {
        return this;
    }
    var midRes = this.times(Math.floor(n/2));
    midRes += midRes;
    if ( n % 2 ) {
        midRes += this;
    }
    return midRes;
}

StringMul4.js

/* based on string doubling by loop */
String.prototype.times = function(n) {
    var s = this, total = "";
    while(n > 0) {
	if (n % 2 == 1) total += s;
	if (n == 1) break;
	s += s;
	n = n>>1;
    }
    return total;
};