Methods

Question 1

Imports a library as an object

Answer 1

node require(library)
ie let obj = require(‘readline-sync’)

Question 1

destructive, pushes a new element to the end of an array.

Answer 1

Array.push()

Question 2

non-destructive, returns a brand new array that contains all the elements from the original array followed by all of the arguments passed to it:

Answer 2

Array.concat()

Question 3

destructive, changes the contents of an array by removing or replacing existing elements and/or adding new elementsin place

Answer 3

Array.splice(start, deleteCount)

Question 4

non-destructive, creates a new array populated with the results of calling a provided function on every element in the calling array.

Answer 4

Array.map()

Question 5

non-destructive, returns a new array that includes all elements from the calling array for which the callback returns a truthy value.

Answer 5

Array.filter()

Question 6

non-destructive, reduces the contents of an array to a single value.

Answer 6

Array.reduce()

reducetakes two arguments: a callback function and a value that initializes something called theaccumulator.

Question 7

non-destructive

determines whether an array includes a given element

Answer 7

Array.includes()

Question 8

non-destructive, searches an array for an element with a given value and returns the index of the found element. If the element is not found,returns-1.

Answer 8

Array.indexOf()

Question 9

destructive, rearranges the elements of an array in sequence. It returns a sorted array.

Answer 9

Array.sort()

Question 10

non-destructive, extracts and returns a copied portion of the array. It takes two optional arguments. The first is the index at which extraction begins, while the second is where extraction ends (non inclusive of the last index)

Answer 10

Array.slice()

Question 11

destructive, reverses the order of an array.

Answer 11

Array.reverse()

Question 12

This static method returns an object’s keys as an array. You can iterate over that array using any technique that works for arrays.

Answer 12

Object.keys()

returns the object’s own keys: it does not include any keys from the prototype objects.

Question 13

This static method extracts the values from every own property in an object to an array:

Answer 13

Object.values()

Question 14

This static method returns an array of nested arrays. Each nested array has two elements: one of the object’s keys and its corresponding value:

Answer 14

Object.entries()

Question 15

merges two or more objects to a single object by mutating the first object. Returns the new object.

Answer 15

Object.assign(objA, objB)
can be used with an empty object in first place if you want to simply make a copy and not modify the first object.

Question 16

This method checks if some elements exists in an array, and returnstrueorfalse. This is somewhat similar to the concept of theincludes()method, except the argument is a function and not a string.

Answer 16

.some()

Question 17

method loops through the array, checks every item, and returnstrueorfalse. Same concept assome(). Except every item must satisfy the conditional statement, otherwise, it will returnfalse.

Answer 17

.every()

Question 18

This method is responsible for changing all elements on the array to a static value, starting from the first index (set as 0) to the last index. During this process, updates will finish and return a reference array to the original.

Answer 18

.fill()