JS.16.13 Mid-level

More commonly asked utilities

Comes up in: Coding

This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.

What it covers

promisify
run promises in sequence (mapSeries)
makeCancelable
clearAllTimeouts via a timer registry
localStorage with expiry (TTL)
Koa-style middleware compose
deep camelCase/snake_case key conversion
Object.assign polyfill
a JSON.parse subset (recursive descent)

Words you will know

recursive descent parsermiddleware

What you will practise

implement all 9 with tests