I'm interviewing for a Front End Engineer position currently and I've been coding various examples in order to practice. Here are some links to various coding examples I wrote in case anyone else finds them useful (they aren't supposed to be 100% correct):

Dialog modal: https://codepen.io/anon/pen/XOdyxL?editors=0010

Undo/Redo: https://codepen.io/anon/pen/omjMro?editors=0010

Async Task Queue: https://codepen.io/anon/pen/OdbNNo?editors=0010

setTimeout with requestAnimationFrame: https://codepen.io/anon/pen/wNzZoP?editors=0110

Blocking vs Parallel (promises): https://codepen.io/anon/pen/bzBpxX?editors=1010

Evented model attrs: https://codepen.io/anon/pen/pGNbvE?editors=0010

Lisp-like interpreter: https://codepen.io/anon/pen/ErNyPQ?editors=0010

Async Generator Functions: https://codepen.io/anon/pen/RvoRLX?editors=1010

Call function only once (closure): https://codepen.io/anon/pen/ZwBOor?editors=0010

Fade in/out with requestAnimationFrame: https://codepen.io/anon/pen/aPZqBO?editors=0010

DOM Events Playground: https://codepen.io/anon/pen/aXBpmY?editors=1000

Datepicker: https://codepen.io/anon/pen/yzNVzg?editors=0010

Click dropdown menu: https://codepen.io/anon/pen/ZVgrOb?editors=0010

Tooltip: https://codepen.io/anon/pen/VgmZGd?editors=0110

Deck of cards: https://codepen.io/anon/pen/YaOYyL?editors=0010

Autocomplete: https://codepen.io/anon/pen/rzbPQM?editors=0010

Flexbox chat thread layout: https://codepen.io/anon/pen/jdMJvG?editors=0010

Tabs: https://codepen.io/anon/pen/PVNdBx?editors=0010

Simple slider: https://codepen.io/anon/pen/qgqbKb?editors=0010

Hover menu: https://codepen.io/anon/pen/roMePa

Fade up CSS transition: https://codepen.io/anon/pen/zywpXZ?editors=0110

Arrow-up/arrow-down: https://codepen.io/anon/pen/pWmpRB?editors=0010

Form validation: https://codepen.io/anon/pen/dVKGRR?editors=0010

On focus place label above: https://codepen.io/anon/pen/eGgjJx?editors=1100