Practice by framework

Questions List

• Describe the difference between `<script>`, `<script async>` and `<script defer>`

  Importance

  High

  Topics

  HTMLJAVASCRIPT

  Users completed

  3043 completed
• Explain how prototypal inheritance works

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  2221 completed
• Explain how `this` works in JavaScript

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  2093 completed
• What are the differences between variables created using `let`, `var` or `const`?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  2220 completed
• What is the difference between `==` and `===` in JavaScript?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  2132 completed
• What's the difference between a variable that is: `null`, `undefined` or undeclared?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1889 completed
• What's the difference between `.call` and `.apply`?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1855 completed
• Describe the difference between a cookie, `sessionStorage` and `localStorage`.

  Importance

  High

  Topics

  HTMLJAVASCRIPT

  Users completed

  1938 completed
• Can you offer a use case for the new arrow => function syntax?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  848 completed
• Describe event bubbling

  Importance

  High

  Topics

  JAVASCRIPTHTML

  Users completed

  1592 completed
• Describe event capturing

  Importance

  High

  Topics

  JAVASCRIPTHTML

  Users completed

  78 completed
• Explain event delegation

  Importance

  High

  Topics

  JAVASCRIPTHTML

  Users completed

  1509 completed
• Explain `Function.prototype.bind`

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1383 completed
• Explain "hoisting"

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1502 completed
• Explain the difference between synchronous and asynchronous functions

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1375 completed
• Difference between: `function Person(){}`, `const person = Person()`, and `const person = new Person()`?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  781 completed
• Explain AJAX in as much detail as possible

  Importance

  Mid

  Topics

  JAVASCRIPTNETWORK

  Users completed

  753 completed
• Explain how JSONP works (and how it's not really Ajax)

  Importance

  Mid

  Topics

  JAVASCRIPTNETWORKSECURITY

  Users completed

  561 completed
• Explain the difference between mutable and immutable objects

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  623 completed
• Explain the differences between CommonJS modules and ES modules

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  27 completed
• Explain the differences on the usage of `foo` between `function foo() {}` and `var foo = function() {}`

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  697 completed
• Explain what a single page app is and how to make one SEO-friendly

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  625 completed
• How do you abort a web request using `AbortController`?

  Importance

  Mid

  Topics

  JAVASCRIPTNETWORK

  Users completed

  29 completed
• How does JavaScript garbage collection work?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  26 completed
• What advantage is there for using the arrow syntax for a method in a constructor?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  551 completed
• What are iterators and generators and what are they used for?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  20 completed
• What are JavaScript polyfills for?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  23 completed
• Can you describe the main difference between a `.forEach` loop and a `.map()` loop?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  562 completed
• Can you give an example for destructuring an object or an array?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  517 completed
• Can you give an example of a curry function and why this syntax offers an advantage?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  357 completed
• Create a for loop that iterates up to `100` while outputting **"fizz"** at multiples of `3`, **"buzz"** at multiples of `5` and **"fizzbuzz"** at multiples of `3` and `5`

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  412 completed
• Difference between document `load` event and document `DOMContentLoaded` event?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  404 completed
• ES2015 Template Literals offer a lot of flexibility in generating strings, can you give an example?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  412 completed
• Explain the same-origin policy with regards to JavaScript

  Importance

  Low

  Topics

  JAVASCRIPTNETWORK

  Users completed

  422 completed
• Explain why the following doesn't work as an IIFE: `function foo(){ }();`. What needs to be changed to properly make it an IIFE?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  398 completed
• How can you share code between files?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  385 completed
• How do you organize your code?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  364 completed
• What are JavaScript object getters and setters for?

  Importance

  Topics

  JAVASCRIPT

  Users completed

  16 completed
• What are JavaScript object property flags and descriptors?

  Importance

  Topics

  JAVASCRIPT

  Users completed

  16 completed
• What are `Symbol`s used for?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  51 completed
• What are the differences between `Map`/`Set` vs `WeakMap`/`WeakSet`?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  42 completed
• What are the pros and cons of using Promises instead of callbacks?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1254 completed
• What are the various ways to create objects in JavaScript?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  47 completed
• What are workers in JavaScript used for?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  35 completed
• What is a closure, and how/why would you use one?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1226 completed
• What is event loop?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1206 completed
• What language constructions do you use for iterating over object properties and array items?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  575 completed
• What's a typical use case for anonymous functions?

  Importance

  High

  Topics

  JAVASCRIPT

  Users completed

  1201 completed
• What are server-sent events?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  17 completed
• What are the differences between ES2015 classes and ES5 function constructors?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  527 completed
• What are the differences between `XMLHttpRequest` and `fetch()`?

  Importance

  Mid

  Topics

  JAVASCRIPTNETWORK

  Users completed

  16 completed
• What is the definition of a higher-order function?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  592 completed
• What is `"use strict";`?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  563 completed
• What's the difference between an "attribute" and a "property"?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  538 completed
• What's the difference between feature detection, feature inference, and using the UA string?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  430 completed
• Why is it, in general, a good idea to leave the global scope of a website as-is and never touch it?

  Importance

  Mid

  Topics

  JAVASCRIPT

  Users completed

  509 completed
• What are some of the advantages/disadvantages of writing JavaScript code in a language that compiles to JavaScript?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  347 completed
• What are the advantages and disadvantages of using AJAX?

  Importance

  Low

  Topics

  JAVASCRIPTNETWORK

  Users completed

  361 completed
• What are the benefits of using spread syntax and how is it different from rest syntax?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  392 completed
• What are the various data types in JavaScript?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  19 completed
• What do you think of AMD vs CommonJS?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  316 completed
• What is the extent of your experience with Promises and/or their polyfills?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  355 completed
• What tools and techniques do you use for debugging JavaScript code?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  422 completed
• What's the difference between host objects and native objects?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  376 completed
• When would you use `document.write()`?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  353 completed
• Why is extending built-in JavaScript objects not a good idea?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  401 completed
• Why is it called a Ternary expression, what does the word "Ternary" indicate?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  492 completed
• Why would you use something like the `load` event?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  407 completed
• Why might you want to create static class members?

  Importance

  Low

  Topics

  JAVASCRIPT

  Users completed

  411 completed