Javascript topics

Question 1

what are callbacks?

Answer 1

callbacks is when we pass a function as an arguement in another function to be invoked within that function. often use like do this thing then ___. can be sync or async

Question 2

what are promises?

Answer 2

promises are a way we can handle async functions within javascript. they return an object which can be either Pending, Fulfilled, Rejected. The Promise object supports two properties: state and result.

While a Promise object is “pending” (working), the result is undefined.

When a Promise object is “fulfilled”, the result is a value.

When a Promise object is “rejected”, the result is an error object.

Question 3

describe a closure

Answer 3

a func defined in a func that relies on data which lives in the outer func but when the inner func is returned it remembers the outer scope data. boss

Question 4

what is the difference between var, const, and let

Answer 4

const is block scoped and cant be redefined, let is block scoped, var is function scoped

Question 5

What are the different data types present in javascript?

Answer 5

idk know them all off the top of my head. or Number.
String.
Boolean.
Null.
Undefined.
BigInt.
Symbol.
Object.

Question 6

what is this keyword in javascript.

Answer 6

just a reference to the execution context