concat arrays with forEach

Question

I have two arrays that are made up of 20 arrays of objects. Like this:

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}
  ]
];

I want the end result to be:

[
    [
    {'x':0,'y':0},
    {'x':0,'y':0},
    {'x':0,'y':0},
    {'x':0,'y':0}
    ],
...
];

So I'm attaching two items in each array, meaning each array should contain four objects now.

What I tried was:

      var array3 = array1;

      array3.forEach(function(item,i) {
         item.concat(array2[i])
      })

But nothing was appended

Question

Is there a less painstaking approach to concat items iteratively?

Answer 1

This is a fairly typical "zip" operation, can can be accomplished using map.

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}
  ]
];

var result = array1.map( (item,i) => item.concat(array2[i]));
console.log(result);