- Explain event delegation.
- Explain how
this works in JavaScript.- Can you give an example of one of the ways that working with
this has changed in ES6?
- Explain how prototypal inheritance works.
- What is the difference between a variable that is:
null, undefined or undeclared?- How would you go about checking for any of these states?
- What is a closure, and how/why would you use one?
- What language constructions do you use for iterating over object properties and array items?
- Can you describe the main difference between the
Array.forEach() loop and Array.map() methods and why you would pick one versus the other?- Сan you describe other popular methods for iterating over arrays?
- What is a typical use case for anonymous functions?
- What is the difference between host objects and native objects?
- Explain the difference between:
function Person(){}, var person = Person(), and var person = new Person()? - Explain the differences on the usage of
foo between function foo() {} and var foo = function() {} - Can you explain what
Function.call and Function.apply do? What is the notable difference between the two? - Explain
Function.prototype.bind. - What is the difference between feature detection, feature inference, and using the UA string?
- Explain “hoisting”.
- What is type coercion? What are common pitfalls of relying on type coercion in JavaScript code?
- Describe event bubbling.
- Describe event capturing.
- What is the difference between an “attribute” and a “property”?
- What are the pros and cons of extending built-in JavaScript objects?
- What is the difference between
== and ===? - Explain the same-origin policy with regards to JavaScript.
- Why is it called a Ternary operator, what does the word “Ternary” indicate?
- What is strict mode? What are some of the advantages/disadvantages of using it?
- What are some of the advantages/disadvantages of writing JavaScript code in a language that compiles to JavaScript?
- What tools and techniques do you use debugging JavaScript code?
- Explain the difference between mutable and immutable objects.
- What is an example of an immutable object in JavaScript?
- What are the pros and cons of immutability?
- How can you achieve immutability in your own code?
- Explain the difference between synchronous and asynchronous functions.
- What is event loop?
- What is the difference between call stack and task queue?
- What are the differences between variables created using
let, var or const?- Can you change a property of an object defined via
const? How you can change this behavior?
- What are the differences between ES6 class and ES5 function constructors?
- Can you offer a use case for the new arrow
=> function syntax? How does this new syntax differ from other functions? - What advantage is there for using the arrow syntax for a method in a constructor?
- What is the definition of a higher-order function?
- Can you give an example for destructuring an object or an array?
- Can you give an example of generating a string with ES6 Template Literals?
- Can you give an example of a curry function and why this syntax offers an advantage?
- What are the benefits of using
spread syntax and how is it different from rest syntax? - How can you share code between files?
- Why you might want to create static class members?
- What is the difference between
while and do-while loops in JavaScript? - What is a promise? Where and how would you use promise?
- Discuss how you might use Object Oriented Programming principles when coding with JavaScript.
- What is the difference between
event.target and event.currentTarget? - What is the difference between
event.preventDefault() and event.stopPropagation()?
Coding questions
duplicate([1,2,3,4,5]);
- 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 - What will be returned by each of these?
console.log("hello" || "world")
console.log("foo" && "bar")
- Write an immediately invoked function expression (IIFE)