title: variable assignment inside 'IF' condition
body: <p>in php, something like this is fine:</p>
  
  <pre><code>&lt;?php
      if ( !$my_epic_variable = my_epic_function() ){
          // my epic function returned false
          // my epic variable is false
          die( "false" );
      }
  
      echo $my_epic_variable;
  ?&gt;
  </code></pre>
  
  <p>I suppose is a shorter way of doing:</p>
  
  <pre><code>$my_epic_variable = my_epic_function();
  if ( !$my_epic_variable ){
          die( "false" );
  }
  </code></pre>
  
  <p>Can this be done is javascript? I've tried to no success, wasnt sure if there was some kind of special syntax or something</p>