I want to learn JavaScript and I intend to use it for work not as a hobby, I want to create useful things and I want them to work on everything (computers, smartphones, etc) but I'm very confused so please I ask you for your help.

Yesterday I bought a book (**Learning JavaScript**, third edition by Ethan Brown) and I was enjoying the book and everything was great until I reach a part titled "Writing ES6 Today" which basically said, this is the new thing but nobody is using it and it's not supported everywhere, so at that point I stop reading it.

Because I don't have more money I looked for something free and found **You Don't Know JS**, so I started reading it and at some point it said that it will assume ES6, but the other guy said that the web is not ready for this so should I learn it or no.

So I decided to inform myself and then it's when things got really confusing.

So the general opinion in the places that I looked was that you should learn ES5 and then learn ES6, but things got more interesting when someone said that you should learn plain JavaScript and then ECMAScript, but wait aren't ES5 and ES6 versions of JavaScript?

So I ask:

* Are JavaScript and ECMAScript mutually exclusive?
* Should I stick with my book or get another?
* is JavaScript: The Definitive Guide, 6th Edition a good book or is it
too old?