JavaScript how to append one array to another

The javascript Array function concat() joins two arrays and returns the new array, so you end up with 3 arrays, the original, the one being appended, and the concatenated array.

This code below extends the array object by adding an append(array) method.  This will append the passed array to the existing array, without creating an intermediate array.

Array.prototype.append = function(a) {
return this;


[ 0, 1 ].append([ 2, 3 ])
[ 0, 1 ].append([ 2, 3 ]).append([ 4, 5 ])

Note: that this method does not necessarily give the best performance.


About austinfrance

Technical Developer @ RedSky IT / Explorer Software
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