Global variables, which is accessed via different html files are reset everytime I open the page?

Question

So, I just want to define some variables, and change their value according to the user action(page visit)

script_variables.js

var visitedPage1 = 0 ;
var visitedPage2 = 0;
var visitedPage3 = 0;

script_home.js

window.onload = function() {
 
    console.log(visitedPage1);


 }

Page1.html

<script src="/js/script_variables.js"></script>
<script>
       
window.onload = function() {
         
visitedPage1 = 1;
      
       }

Home.html

<script src="/js/script_variables.js"></script>
<script src="/js/scriptHome.js"></script>

Even though, I can change assign 1 into visitedPage1, when I came back to the home, console shows 0, I guess it reloads the script_variable.js again and assign 0.

How should I approach this problem and sorry for this noob question. thank you