Repeat a string in JavaScript a number of times

These days, the repeat string method is implemented almost everywhere. (It is not in Internet Explorer.) So unless you need to support older browsers, you can simply write:

"a".repeat(10)

Before repeat, we used this hack:

Array(11).join("a") // create string with 10 a's: "aaaaaaaaaa"

(Note that an array of length 11 gets you only 10 "a"s, since Array.join puts the argument between the array elements.)

Simon also points out that according to this jsperf, it appears that it's faster in Safari and Chrome (but not Firefox) to repeat a character multiple times by simply appending using a for loop (although a bit less concise).

In a new ES6 harmony, you will have native way for doing this with repeat. Also ES6 right now only experimental, this feature is already available in Edge, FF, Chrome and Safari

"abc".repeat(3) // "abcabcabc"

And surely if repeat function is not available you can use old-good Array(n + 1).join("abc")

Convenient if you repeat yourself a lot:

String.prototype.repeat = String.prototype.repeat || function(n){
  n= n || 1;
  return Array(n+1).join(this);
}

alert(  'Are we there yet?\nNo.\n'.repeat(10)  )