Avoid setInterval and use MutationObserver

[mattiagalati]

In your code you make use of setInterval to check if left nav panel is loaded, and clear that interval when the dom you need is ready.
I would suggest you to use a MutationObserver instead, in order to tell the browser to notify your code when the dom is ready.

[kevinwucodes]

I've never used MutationObserver before. I'll look into it, thanks.

[kevinwucodes]

I looked at this and it appears that MutationObserver can't observe nodes if that node doesn't already exist. Not sure if using MutationObserver is still achieveable.