adding array to an array using javascript

It depends on weather you want to add the items from Arr1, Arr2 and Arr3 or add the actuall arrays.

For example, this solution adds the items;

function add(source, target) {
    for(var i = 0; i < source.length; ++i)
        target.push(source[i]);
}

var Arr_all = [];
var Arr1 = [1, 2, 3];
var Arr2 = [4, 5, 6];
var Arr3 = [7, 8, 9];

add(Arr1, Arr_all);
add(Arr2, Arr_all);
add(Arr3, Arr_all);

This leaves the content of Arr_all as;
[1, 2, 3, 4, 5, 6, 7, 8, 9]

But if you want to add the actual arrays you'd do;

var Arr1 = [1, 2, 3];
var Arr2 = [4, 5, 6];
var Arr3 = [7, 8, 9];

var Arr_all = [Arr1, Arr2, Arr3];

That leaves the content of Mcode>Arr_all as;
[
[1, 2, 3],
[4, 5, 6],
[7, 8, 9]
]

Hope this helps,
Fredrik