check if a browser tab is already open so I don't make extra tabs

Question

When a user adds an item to our shopping cart it opens our store in a new tab. Different websites oddly enough.

I would like to check if the tab is already open and then repopulate it it with the second item instead of opening another tab with the updated cart.

Is there a way to check this with js? I imagine I can track that we opened the tab but I don't see how I can confirm that it wasn't closed in the time between adding items to the cart without doing some ajax requests pinging both pages etc. Which seems like overkill.

So simply how do you check if a browser tab is already open?

Edited with a solution: First:

var tab = window.open('http://google.com','MyTab');

Then:

if(tab) {
  var tab = window.open('http://yahoo.com','MyTab');
}

Answer 1

window.open has the following parameters: var tab = window.open(url, name, specs, replace) As long as you use the same name the url will be loaded into that window/tab.

If you wanted to keep the descriptor/reference (tab above), that window.open returns, once the user refreshes the page, that reference is lost.