title: the every method does not work in javascript
body: <p>Firstly, the <code>.includes</code> method does not work with my framework, so I omit this here.
  I have <code>checkIn(el,ar)</code> function to check if <code>el</code> in <code>ar</code> like this:</p>
  
  <pre><code>function checkIn(el){
  var check = false;
     for (i = 0; i &lt; ar.length; i++){
       if(el === ar[i]){
       check = true;
       break;
     };
    };
   return check;
   };
  </code></pre>
  
  <p>it works normaly. Then I want to use the <code>.every</code> method to check if every element of a given array is in another given array</p>
  
  <pre><code>var x = [1,2,3];
  var y = [1,2,3,4,5];
  var check = x.every(checkIn(y))
  </code></pre>
  
  <p><code>check</code> needs to be true, but it doesn't work?</p>