Browser Javascript:- Webpage Edits, Control, Simulate via JavaScript | Small project

I need a knowledgeable JavaScript coder to make necessary changes and control features on an existing webpage ( Developer Mode f12 console page). It is a small adhoc task (within an hour) for an online gaming website (Casino) for which javascript is already there in discussion forums but need to make edits and additions to it from a knowledgeable JavaScript coder.

You should have:

- Proven experience in web development.
- Proficient in JavaScript.