Let’s say the following are our arrays:  [20, 40, 60]
[80, 100, 120] To merge them, JavaScript provides the Array.concat() method. The return value of this method is a new array with the result of concatenated arrays:  var res = arr1.concat(arr2); Let us now merge the above two arrays:
Merge JavaScript Arrays
The output displays the merged arrays:  Array 1 = 20,40,60
Array 2 = 80,100,120
Merged Arrays = 20,40,60,80,100,120