intercept back in javascript

To intercept the back button in JavaScript, you can use the window.onpopstate event.

index.tsx
window.onpopstate = function(event) {
  // your logic here
};
62 chars
4 lines

The window.onpopstate event is triggered whenever the user navigates backwards or forwards through the browser history, by clicking the back or forward buttons, or using the browser history API.

Inside this event, you can write your logic to handle the user's action, such as redirecting the user to a specific page or displaying a message. You can also access the event object to get information about the history change, such as the state object that was passed when using the history.pushState() method.

index.tsx
window.onpopstate = function(event) {
  if (event.state && event.state.page == 'homepage') {
    // user navigated back to homepage
    alert('Welcome back to the homepage!');
  } else {
    // user navigated to a different page
    window.location.href = event.target.location.href;
  }
};
291 chars
10 lines

In the example above, the logic checks if the user navigated back to the homepage, and displays a welcome message if they did. If the user navigated to a different page, the logic redirects them to that page.