When anchor part is changed, then the onhashchange event occurs. You can try to run the following code to learn how to implement onhashchange event in JavaScript.
Example
<!DOCTYPE html> <html> <body onhashchange="newFunc"> <button onclick="functionChange()">Click to change anchor</button> <script> function functionChange() { location.hash = "about"; var hash = location.hash; document.write("The anchor part is now: " + hash); } // If the achor part is changed function newFunc() { alert("Anchor part changed!"); } </script> </body> </html>