title: How to return string in JavaScript without Typing string
body: <p>I have been writing JavaScript for long time but I just met this piece of code which renders to "mk break fix", how this can work and what if I want it to render another string?</p>
  
  <p>Please look this code:</p>
  
  <pre><code>([].map+0)[9]+([].keys+0)[9]+
  (top+0)[7]+(typeof!1)[0]+(!0+'')[1]+
  (!1+'')[4]+(-{}+'')[1]+([].keys+0)[9]+
  (top+0)[7]+(''.fixed+0).slice(9,12) 
  
  </code></pre>
  
  <p>So how does it happen to even return a text here?</p>