JS

Question 1

Explain event delegation

Answer 1

a

Question 2

Explain how this works in JavaScript

Answer 2

a

Question 3

Explain how prototypal inheritance works

Answer 3

a

Question 4

What do you think of AMD vs CommonJS?

Answer 4

a

Question 5

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

Answer 5

a

Question 6

What’s the difference between a variable that is: null, undefined or undeclared?
How would you go about checking for any of these states?

Answer 6

a

Question 7

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

Answer 7

a

Question 8

What’s a typical use case for anonymous functions?

Answer 8

a

Question 9

How do you organize your code? (module pattern, classical inheritance?)

Answer 9

a

Question 10

What’s the difference between host objects and native objects?

Answer 10

a

Question 11

Difference between: function Person(){}, var person = Person(), and var person = new Person()?

Answer 11

a

Question 12

What’s the difference between .call and .apply?

Answer 12

a

Question 13

What’s the difference between .call and .apply?

Answer 13

a

Question 14

When would you use document.write()?

Answer 14

a

Question 15

What’s the difference between feature detection, feature inference, and using the UA string?

Answer 15

a

Question 16

Explain Ajax in as much detail as possible.

Answer 16

a

Question 17

What are the advantages and disadvantages of using Ajax?

Answer 17

a

Question 18

Explain how JSONP works (and how it’s not really Ajax).

Answer 18

a

Question 19

Have you ever used JavaScript templating?

Answer 19

a

Question 20

Explain “hoisting”.

Answer 20

a

Question 21

Describe event bubbling.

Answer 21

a

Question 22

What’s the difference between an “attribute” and a “property”?

Answer 22

a

Question 23

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

Answer 23

a

Question 24

Difference between document load event and document DOMContentLoaded event?

Answer 24

a

Question 25

What is the difference between == and ===?

Answer 25

a

Question 26

Explain the same-origin policy with regards to JavaScript.

Answer 26

a

Question 27

Why is it called a Ternary expression, what does the word “Ternary” indicate?

Answer 27

a

Question 28

What is “use strict”;? what are the advantages and disadvantages to using it?

Answer 28

a

Question 29

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

Answer 29

a

Question 30

Why would you use something like the load event? Does this event have disadvantages? Do you know any alternatives, and why would you use those?

Answer 30

a

Question 31

Explain what a single page app is and how to make one SEO-friendly.

Answer 31

a

Question 32

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

Answer 32

a

Question 33

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

Answer 33

a

Question 34

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

Answer 34

a

Question 35

What tools and techniques do you use debugging JavaScript code?

Answer 35

a

Question 36

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

Answer 36

a

Question 37

Explain the difference between mutable and immutable objects.

Answer 37

a

Question 38

What is an example of an immutable object in JavaScript?

Answer 38

a

Question 39

What are the pros and cons of immutability?

Answer 39

a

Question 40

How can you achieve immutability in your own code?

Answer 40

a

Question 41

Explain the difference between synchronous and asynchronous functions.

Answer 41

a

Question 42

What is event loop?

Answer 42

a

Question 43

What is the difference between call stack and task queue?

Answer 43

a

Question 44

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

Answer 44

a