2. What's the difference between `undefined` and `null`?
3. What does the `&&` operator do?
4. What does the || operator do?
5. Is using the + or unary plus operator the fastest way in converting a string to a number?
6. What is the DOM?
7. What is Event Propagation?
8. What's Event Bubbling?
9. What's Event Capturing?
10. What's the difference between event.preventDefault() and event.stopPropagation() methods?
11. How to know if the event.preventDefault() method was used in an element?
12. Why does this code obj.someprop.x throw an error?
13. What is event.target?
14. What is event.currentTarget?
15. What's the difference between == and === ?
17. What does the !! operator do?
18. How to evaluate multiple expressions in one line?
19. What is Hoisting?
20. What is Scope?
21. What are Closures?
23. What does "use strict" do?
25. What is the prototype of an object?
26. What is an IIFE, what is the use of it?
27. What is the use Function.prototype.apply method?
28. What is the use Function.prototype.call method?
29. What's the difference between Function.prototype.apply and Function.prototype.call?
30. What is the usage of Function.prototype.bind?
32. What are Higher Order Functions?
33. Why are functions called First-class Objects?
34. Implement the Array.prototype.map method by hand.