Fundamentals

Question 1

What are assignment operators?

Answer 1

Assign a value to its left operand based on the value of its right operand.

+= addition assignment
-= subtraction assignment
*= multiplication assignment
/= division assignment

Question 2

What is string interpolation?

Answer 2

Process of evaluating string literals containing one or more placeholders (expressions, variables, etc)

Performed using template literals like:
Hi ${userName} welcome to the app;

Performed using string concatenation like:
‘Hi ‘ + userName + ‘ welcome to the app’;

Question 3

What are variables and how can you declare them?

Answer 3

Variables are used to store data in memory and ensure code re-usability. They are referenced by name.

Types: const, let, and previously var

Question 4

What is a template literal?

Answer 4

Strings that allow embedded expressions. Use backticks instead of quotes.

let name = “Kristin”;
console.log(Hello, ${name});

console.log(Billy is ${6+8} years old.);

Question 5

let

Answer 5

creates a local variable that can be re-assigned
initialization is optional
will contain ‘undefined’ if nothing is assigned to it

Question 6

const

Answer 6

creates a local variable that cannot be re-assigned
initialization is required
will throw a runtime error if not assigned

Question 7

String Concatenation

Answer 7

Creates a new string by concatenating multiple other strings together using the addition+ operator

let welcomeMsg = ‘Hi ‘ + userName + ‘ welcome to the app’

Question 8

console.log()

Answer 8

used to log or print messages, objects, and other information to the console

console.log(‘some important message’)

Question 9

What are methods?

Answer 9

They return information about an object and are called by appending an instance with a period, the method name, and parentheses

Math.random(); //returns a number between 0 -1

Question 10

undefined

Answer 10

a primitive JS value that represents lack of a defined value

Question 11

null

Answer 11

a primitive JS data type that represents the intentional absence of a value

Question 12

Arithmetic Operators

Answer 12

+ addition
- subtraction
* multiplication
/ division

% modulo - returns the number that remains after the right-hand number divides into the left-hand number as many times as it can