Repeating a string with vanilla JavaScript

Last week, we looked at how to check if a string starts with or ends with with a specific substring.

Today, we’re going to look at how to repeat a string a certain number of times.

Let’s dig in.

The String.repeat() method

This method does exactly what it says on the label.

You call it on a string you want to repeat, and pass in the number of times to repeat as an argument. That’s it. That’s the whole method.

var beetlejuice = 'Beetlejuice ';

// returns "Beetlejuice Beetlejuice Beetlejuice "
beetlejuice.repeat(3);

Valid numbers

You can’t pass in a negative number. If you pass in a float (a number with decimal points), it will get rounded down to the nearest whole number.

// returns Uncaught RangeError: Invalid count value
beetlejuice.repeat(-1);

// returns "Beetlejuice Beetlejuice Beetlejuice "
beetlejuice.repeat(3.7);

Browser compatibility

The String.repeat() method works in all modern browsers, including MS Edge, but has no IE support. You can push support back to IE9 with a polyfill.