You Don't Know JS Yet (book study)

Question 1

What is interpolation in JS?

Answer 1

Interpolation is a way to insert values into string literals in a concise, easily readable way.

Ex:
firstName = ‘Katy Perry’;

console.log(${firstName} is Kim Jon Un's favorite musical artist);

Will return: “Katy Perry is Kim Jon Un’s favorite musical artist.”

Question 2

bigint

Answer 2

Big-integer primitive type

Used for storing arbitrarily large numbers.

Question 3

Primitive values

Answer 3

A primitive value is data that is not an object and has no methods.

Strings 
Numbers 
Booleans 
Null 
Undefined

Question 4

Symbols

Answer 4

A special-purpose value, used almost exclusively as special keys on objects.

Mostly used in low-level code such as in libraries and frameworks.

Question 5

Arrays

Answer 5

A special type of object comprised of ordered and numerically indexed list of data.

Array elements are accessed numerically.

Can hold any value type - primitive or object, other arrays, even functions!

Question 6

Functions, like arrays, are a sub-type of ____.

Answer 6

Object

Question 7

Objects

Answer 7

Unordered, keyed collection of any various values.

A element is accessed by string location name (key or property), not by a numeric position.

Question 8

Value Type Determination

Answer 8

Used to distinguish values.

TYPEOF operator tells you the value’s built-in type, be it primitive, object or otherwise.

Question 9

Coercion

Answer 9

Converting one value type to another (like a string to a number)

Question 10

const

Answer 10

Must be given a value at the moment it’s declared

Cannot be re-assigned.

Question 11

let

Answer 11

Similar to var, but with more limited access. (known as block scoping)

Question 12

Why is it ill-advised to use const with object values?

Answer 12

Those values can still be changed, even though the variable can’t be reassigned. This could lead to potential confusion down the line.