title: concat arrays with forEach
body: <p>I have two arrays that are made up of 20 arrays of objects. Like this:</p>
  
  <pre><code>var array1 = [
    [
      {'x':0,'y':0},
      {'x':0,'y':0}
    ],
    [
      {'x':1,'y':1},
      {'x':1,'y':1}
    ],
  ...
    [
      {'x':19,'y':19},
      {'x':19,'y':19}
    ]
  ];
  
  var array2 = [
    [
      {'x':0,'y':0},
      {'x':0,'y':0}
    ],
    [
      {'x':1,'y':1},
      {'x':1,'y':1}
    ],
  ...
    [
      {'x':19,'y':19},
      {'x':19,'y':19}
    ]
  ];
  </code></pre>
  
  <p>I want the end result to be:</p>
  
  <pre><code>[
      [
      {'x':0,'y':0},
      {'x':0,'y':0},
      {'x':0,'y':0},
      {'x':0,'y':0}
      ],
  ...
  ];
  </code></pre>
  
  <p>So I'm attaching two items in each array, meaning each array should contain four objects now.</p>
  
  <p>What I tried was:</p>
  
  <pre><code>      var array3 = array1;
  
        array3.forEach(function(item,i) {
           item.concat(array2[i])
        })
  </code></pre>
  
  <p>But nothing was appended</p>
  
  <h2>Question</h2>
  
  <p>Is there a less painstaking approach to concat items iteratively?</p>