JavaScript Interview Questions
Core JavaScript interview questions covering fundamentals, functions and closures, objects and prototypes, classes and OOP, and asynchronous programming with the event loop.
Topics
- FundamentalsVariables, scope, hoisting, data types and type coercion — the bedrock concepts every JavaScript interview starts with. 2 subtopics
- FunctionsClosures, the `this` keyword, arrow vs regular functions and higher-order functions — the most heavily tested JavaScript topic. 5 subtopics
- Asynchronous JavaScriptCallbacks, promises, async/await and the event loop — how JavaScript handles non-blocking work behind the scenes. 2 subtopics
- Objects & PrototypesObject creation and properties, the prototype chain, prototypal inheritance and how the new operator builds objects — the heart of JavaScript's object model. 4 subtopics
- Classes & OOPES6 class syntax, inheritance with extends and super, static members, private fields, getters/setters and mixins — object-oriented JavaScript built on prototypes. 4 subtopics
- Arrays & IterationCreating and iterating arrays with map, filter and reduce, mutation versus immutability, searching and sorting, and array destructuring and spread — the everyday tools for working with collections in JavaScript. 4 subtopics
- Modern JavaScript (ES6+)The ergonomic features that define modern JavaScript — destructuring and spread/rest, optional chaining and nullish coalescing, template literals and tagged templates, and Symbols for unique keys and protocol hooks. 4 subtopics