tracks
Pick where to put the reps.
Each track is ordered from basics to the parts that go first when you stop using them.
React
Components that render twice, and effects that run when you did not mean them to.
TypeScript
Types that stay after you stop looking at the file, then the interview core — two pointers, a cache that evicts, a retry that backs off. Blanks first, challenges next, then the cases that pin a request down.
Vue.js
Reactivity you can name, and the watcher that watched a value.