Variables declared in script are lost in page

Good morning.

My problem is that I have an old project to which I must fix some things, but this has problems using variables declared as in any other page.

This is the scenario: To avoid putting so much code, the page generates dynamic tabs, when the user clicks on an item within a menu.

Click on Menu, CreateTab - > LoadAspx.

The functionality what it does is to send a complete aspx and show it within tabContent , but I must register the current tab in a variable to know which is active, but the variable declared in the script is not available for use within the aspx that was inserted in tabContent .

I tried using window.variable, but it's the same case.

My Script:

var CurrentActivetab = "";
window.CurrentActivetabW = "";

When creating Dynamic tab it is filled with Pagina.Aspx.

var myCurrenttabId = CurrentActivetab = "";

or

var myCurrenttabId = window.CurrentActivetabW = "";

Thanks for your help, regards.