JS: String.prototype.repeat

New in JS2015.

String.prototype.repeat(count)

repeat a string.

"a".repeat(2) === "aa"

The function can also work on Value Types othe than string. It will first convert this Binding to string, then return count copy of it, joined together.

/* digit 9 to string, then repeat 2 times */
console.log( Reflect.apply( String.prototype.repeat , 9, [2] ) === "99" );

[see JS: Reflect]