Question

I have simple code

sites_from_session = 12;
function function_name () {
    var items_to_send = sites_from_session;
    var template_name = jQuery('#new-site-template-name').val();
    console.log(sites_from_session);
    items_to_send.push(template_name);
    console.log(sites_from_session);
}


function_name();
function_name();
function_name();
function_name();
function_name();
function_name();//...

The problem is that the push method pushes value to both arrays

Where i am wrong?

Answer 1

Arrays do not self clone in JavaScript. When you say something like

arr1 = arr2;

where both arr2 is a valid array, you haven’t made an actual copy of arr2. All you’ve done is create a reference pointer to it for arr1. So when you make a change like

arr1[0] = "some value";

you are (in essence) saying the same thing as

arr2[0] = "some value";

To properly clone a separate copy you need to use this:

var items_to_send = sites_from_session.slice();

This will return a new array that holds all of the items from the original array.