How to add Custom ECB (Context Menu) in SharePoint Online List

Below is the script for adding context menu in SharePoint List

<script language="javascript" type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.8.1/jquery.min.js"></script>  

<script language="javascript" type="text/javascript"> 
    $(document).ready(function() { 
        SP.SOD.executeFunc('sp.js', 'SP.ClientContext', AddCustomUserActionToECB); 
    }); 
    var oListItem;
    function AddCustomUserActionToECB() { 
        //Get the client context,web and list object  
        var clientContext = new SP.ClientContext(); 
        var oWeb = clientContext.get_web(); 
        var oList = oWeb.get_lists().getByTitle('TestList'); 
        var userCustomActionColl = oList.get_userCustomActions(); 
        var oUserCustomAction = userCustomActionColl.add(); 
        oUserCustomAction.set_location('EditControlBlock'); 
        oUserCustomAction.set_sequence(100); 
        oUserCustomAction.set_title("Copy Item"); 
        oUserCustomAction.set_url("/sites/TestSite/sitepages/UserCustomActionLandingPage.aspx?ListId={ListId}&ItemId={ItemId}");
  oUserCustomAction.update();
  clientContext.load(userCustomActionColl);
  clientContext.executeQueryAsync(QuerySuccess, QueryFailure); 
        } 
 
        function QuerySuccess() { 
            console.log("Custom Action added to ECB menu."); 
        } 
 
        function QueryFailure() { 
            console.log('Request failed - ' + args.get_message()); 
        } 
</script>