I won’t re-write all existing blog posts and manuals because of two reasons: I’m too lazy for these things and I’m not feeling that I can do it better.
I’ll leave the references for two topics I’ve found useful for me: variables declarations and modules. I like MDN, so I’ll use it for references.
You don’t need var anymore. OK, you still need if for some cases, but let is great for local variables with a limited scope and const works well if you need a variable which can’t be re-assigned. The value of such a variable could be changed like any mutable variable.