The origins of this code come a bit before jQuery.. when libraries commonly extended existing structure prototypes... Some of those became the basis for the additional methods (map/reduce/filter etc) on Array, and others. JavaScript is very flexible which is a blessing and a curse.

I've been a fan of JS since pretty early on... the DOM differences between IE and NN were really horrible to deal with in the v4 browser days, and until jQuery didn't start to get much better really, where today you really don't need jQuery. It's an evolution here... If you're willing to use transpilers you can go anywhere you like... from BabelJS to ClosureScript, TypeScript, CoffeeScript or others... you can get the style you like.

npm + browserify (or webpack) have made developing modern web applications a dream compared to the past.