title: Using the reduce function to return an array
body: <p>Why is it that when I want to use the push function inside the reduce function to return a new array I get an error. However, when I use the concat method inside the reduce function, it returns a new array with no problem.</p>
  
  <p>All I'm trying to do is pass an array to the reduce function and return the same array.</p>
  
  <pre><code>var store = [0,1,2,3,4];
  
  var stored = store.reduce(function(pV,cV,cI){
    console.log("pv: ", pV);
    return pV.push(cV);
  },[]);
  </code></pre>
  
  <p>This returns an error. But when I use concat: </p>
  
  <pre><code>var store = [0,1,2,3,4];
  
  var stored = store.reduce(function(pV,cV,cI){
    console.log("pv: ", pV);
    return pV.concat(cV);
  },[]);
  </code></pre>
  
  <p>It returns the same array.</p>
  
  <p>Any ideas why?</p>