concat stings

How can I append the value x to x during the below loop? Can I do something like below?



for (i=0;i<n;i++){

x =. x ;

}

Use + instead.

x += "thing to append"

for (var i=0;i<n;i++){
x+=x;
}

x = x + x

is usually faster than +=

If we are speaking about the speed, then a while loop is faster than a for loop, and a pre-increment is faster than a post-increment

var i=0;
while(++i<n){
x=x+x;
}

x = x + x

is usually faster than +=

At the cost of higher maintenance?

If you really want speed, I believe this is the fastest . . . using Array.prototype.join:

// Fill an array of size n with all elements set to x.
// For simplicity, I'll cheat in making it. Use a loop/duff's device if you really care.

x = Array.replicate(n, x).join("");