step:-1 Please login with ftp or cpanel and follow steps next.
Step:-2 Click on the template folder as given below.
Step:- 3 Now open the hostx-child folder.

Step:- 4 Now open the js folder.
Step:- 5 Now you will see this file you need to remove_new from file so that file should like override.js.
Note:- It will automatically include and ready to use when you rename it.
Step:- 6 Now you can write any js script here to override existing or for new feature.