Foundations

Question 1

Scope

Answer 1

1. Global scope
2. Local Scope/Function Scope
3. Block scope

Question 2

Closures

Answer 2

1. How to create closures? a combination of the lexical environment
2. When is it created? creation phase
3. Why do we need closures? data privacy, event handlers, and callback functions.

Question 3

Hoisting

Answer 3

1. Moving declaration to the top(incorrect)
2. Allow you to use a variable before declaring it
3. function expressions are not hoisted
4. Three Types: var(assign undefined), let/const(no initialized), function

Question 4

Event Loop

Answer 4

1. A Design pattern
2. Monitor call stack and the task queue
3. Push event to call stack when it’s empty

Question 5

Task Queue

Answer 5

1. A new JavaScript program or subprogram is executed (such as from a console, or by running the code in a element) directly.
2. An event fires, adding the event’s callback function to the task queue.
3. A timeout or interval created with setTimeout() or setInterval() is reached, causing the corresponding callback to be added to the task queue.

Question 6

Microtasks Queue

Answer 6

1. JavaScript promises
2. Mutation Observer API
3. Can use queueMicrotask() by other third parties libs

Question 7

Macrotasks Queue

Answer 7

Does not exist

Question 8

Lexical Environment

Answer 8

A lexical environment is basically the scope or environment the engine is currently
reading code in. A new lexical environment is created when curly brackets {} are used,
even nested brackets {{…}} create a new lexical environment. The execution context tells
the engine which lexical environment it is currently working in and the lexical scope
determines the available variables.

Question 9

Execution Context

Answer 9

1. A simple environment that the code run-in
2. Code is always in an execution context
3. Two/Three Types, Global/Function and eval
4. Two Stages (creation phase and execution phase)

Question 10

Types

Answer 10

1. Undefined
2. Null
3. Boolean
4. Number
5. BigInt
6. String
7. Symbol
8. Function Object
9. Object

Question 11

Scope Chain

Answer 11

Each execution context that has a link outside of it lexical environment called scope chain.

Question 12

Dynamic Scope

Answer 12

this keyword

Question 13

Primitive values

Answer 13

1. Type
string 
number 
bigint
boolean
null
undefined
symbol  
2. passed by value 
3. copied and passed somewhere else in the memory
4.

Question 14

Non Primitive

Answer 14

1. passed by reference (pointer)
2. To make is primitive we can
   Object.assign
   {…}
3. Only Shallow Copy, not Deep Copy

Question 15

Currying

Answer 15

Currying is a transformation of functions that translates a function from callable as f(a, b, c) into callable as f(a)(b)(c)

Question 16

Programming Paradigms

Answer 16

1. OOP

2. FP