Free practice quiz

JavaScript Engine & React Internals Quiz Questions

A sample of the 10 questions below — instant scoring and an explanation for every answer. No sign-in required to play.

Question 1

What are the two main phases of the JavaScript event loop related to timing?

AMacrotasks and microtasks

BCompile time and runtime

CParsing and linking

DGarbage collection and allocation

Question 2

AUsing too many arrow functions

BUsing const instead of let

CReferences to variables in an outer scope being unintentionally retained longer than needed (e.g., via event listeners not removed)

DUsing template literals

Question 3

AUnnecessary recalculations or re-renders by caching results between renders

BMemory leaks caused by the garbage collector

CNetwork requests from being cached

DCSS from reflowing

↓ Scroll down to answer all 10 and see your score.

Preparing your quiz…