Some JS people (the ones usually with a long beard) hate how kids use frameworks like jQuery and this site is an attempt at telling them "The vanilla JS, i.e. the standard language that all browsers use and your cool jQuery leverage under the hood, is quite capable these days. Use it". They are not quite right, but aren't quite wrong either (IMO). You'll be a dreadful JS programmer if you only know jQuery. JS is sooo different from C (and Java) that if you don't know the core language everything you'll do will be wrong. For starter: there's no block scope. Only function scope.

Every JS programmer should read "JavaScript: The Good Parts" by Douglas Crockford cover to cover - before learning jQuery.