title: How to 'repeat' an array n times
body: <p>In python you can do:</p>
  
  <pre><code>arr = [1,2,3] * 3
  print(arr)
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>[1,2,3,1,2,3,1,2,3]
  </code></pre>
  
  <p>Is there a concise way of doing this in java script? The best I can think of is something like:</p>
  
  <pre><code>let arr2 = [...arr, ...arr, ...arr]
  </code></pre>
  
  <p>but if I wanted to do this 100 times it would be impractical. In python I would just multiply it by 100.</p>