1. I have a page where I want to configure dates by selecting dates with date picker and add to dynamic table using javascript in same page.
2. I have multiple dates in the table but not saved or not clicked submit button yet but clicked on sub tab in same page to navigate to another page and a popup opened saying you have unsaved changes
3. Clicked on stay on same page and the added dates are present on the table and clicked on submit button.

Why instead of submitting the form, it redirects to previously visited tab(sub tab mentioned in step 2)?

Below code is to warn, if there is unsaved data:

var submitted = false;
     
$(document).ready(function() {
  $('#addDates').click( function() {
    submitted=true;
  });
     
  window.onbeforeunload = function () {
    if (!submitted) {
      return 'Do you really want to leave the page?';
    } else {
      window.onbeforeunload = null;
    }
  }
});