Onchaning the url suffix of portal, how can I redirect previous url to new one

[Ayushsnow]

Hi all, hope you are doing good.

We have a custom portal whose url suffix changes from '/abc' to '/cde'. Now I want to redirect everyone who has set their bookmarks of previous(/abc) url to new one(/cde).Can someone give the right solution or alternative for following:-

I've looked in community and found it can be done using JS include/ui script.But my ui script has following as starting line and it does not work for normal code:-

var APPNAME=APPNAME || {};

APINAME= (function(){

"use strict";

and I've no clue about this. Please help.