Extend an Array appending elements of another Array in Javascript

arrayAppend.js

// Shorthand function
Array.prototype.append = function(array) {
  this.push.apply(this, array)
}

// Example
var a = [1,2];
var b = [3,4];

a.append(b); // 'a' bacames [ 1, 2, 3, 4 ]