Hi,

First of all you have to learn Dom structure, jquery.

Understand this class function js Link - https://github.com/odoo/odoo/blob/12.0/addons/web/static/src/js/core/class.js ,

After try to inherit function. add your function.

Refer this example - https://github.com/jsilvestar/web

Regards,

Silvestar

https://www.youtube.com/watch?v=madLEYnuXxo&list=PLrWLVFvgHjCdOVUtoz8lNETFZwU2xz-C2

Hello ,

Check below link

https://www.odoo.com/documentation/12.0/index.html

where you found everything related to odoo.

Regards

Manish