title: for loop without condition checking
body: <p>I was reading through <a href="https://stackoverflow.com/a/4025958/7844349">this question</a>, I am not able to grasp the concept used for the 'for loop'</p>
  
  <p>Generally, syntax of for loop is <code>for(assign value, check condition, increment){}</code>
  They have used the for loop but there is no condition checking, how does this work?</p>
  
  <pre><code>for(var i = arr1.length; i--;) {
      if(arr1[i] !== arr2[i])
          return false;
  }
  </code></pre>