Add two arrays without using the concat method

Question

Here is a sample of what I would like to do

function test(r){
  var arr = ['d','e','f'];
  r.push(arr);
  /*
  More Code
  */
  return r;
}
var result = test(['a','b','c']);
alert(result.length);//I want this to alert 6

What I need to do is pass in an array and attach other arrays to the end of it and then return the array. Because of passing by reference I cannot use array.concat(array2);. Is there a way to do this without using something like a for loop to add the elements one by one. I tried something like r.push(arr.join()); but that did not work either. Also, I would like the option of having objects in the arrays so really the r.push(arr.join()); doesn't work very well.

Answer 1

>>> var x = [1, 2, 3], y = [4, 5, 6];
>>> x.push.apply(x, y) // or Array.prototype.push.apply(x, y)
>>> x
[1, 2, 3, 4, 5, 6]

Alternatively using destructuring you can now do this

//generate a new array
a=[...x,...y];
//or modify one of the original arrays
x.push(...y);