Data Structures/Closures

Question 1

What does the acronym LIFO mean?

Answer 1

Last In, First Out

Question 2

What methods are available on a Stack data structure?

Answer 2

push(), pop(), peek()

Question 3

What must you do to access the value at an arbitrary point in a stack (not just the “top”)?

Answer 3

loop through and iterate through each element top to bottom until you reach desired element

Question 4

What does the acronym FIFO mean?

Answer 4

first in, first out

Question 5

What methods are available on a Queue data structure?

Answer 5

dequeue(), enqueue(value), peek()

Question 6

What must you do to access the value at an arbitrary point in a queue (not just the “front”)?

Answer 6

by using a loop to go through and dequeue elements until you reach the desired element and peek

Question 7

How are linked lists different from an array?

Answer 7

in a linked list the data are stored individually and are ‘linked’ together while arrays hold data together and are accessed using an index

Question 8

How would you access an arbitrary node in a linked list (not just the “head”)?

Answer 8

you need to go through the entire list from the head node until you reach the desired node

Question 8

What are unit tests?

Answer 8

Software where individual units are tested

Question 9

Why is it important to write unit tests?

Answer 9

For detecting bugs and refining the code quality

Question 10

What code should be tested with a unit test? What code is not well suited for unit tests?

Answer 10

testing functions and components, it is not well suited for larger blocks of code and for frontend stuff

Question 11

What is Jest? What are some other popular JavaScript unit testing frameworks?

Answer 11

open-source js testing framework that is used to write unit tests. other testing frameworks include (Mocha, Jasmine, Karma, Ava, etc)

Question 12

In JavaScript, when is scope determined?

Answer 12

Before the code is executed

Question 13

What allows JavaScript functions to “remember” values from their surroundings?

Answer 13

Closures

Question 14

What values does a closure contain?

Answer 14

the function and the object that contains the variables and params of the outer function that were in scope when the inner function was created

Question 15

When is a closure created?

Answer 15

when a function is defined inside another function, and the inner function references a variable from the outer function’s scope

Question 16

How can you tell if a function will be created as a closure?

Question 17

In React, what is one important case where you need to know if a closure was created?

Answer 17

if you have a function with a dependency