Arrays/lists

Question 1

Add to end of array

Answer 1

arr.push(element)

Question 2

Remove from start of array

Answer 2

arr.shift()

Question 3

Remove from end

Answer 3

arr.pop()

Question 4

Remove from middle of array

Answer 4

arr.splice(startIndex, deleteCount)

Question 5

Find length of array

Answer 5

arr.length

Question 6

Check if array includes a value

Answer 6

arr.includes(value)

Question 7

Map array elements

Answer 7

arr.map(element => element * 2)

Question 8

Filter array elements

Answer 8

arr.filter(element => element > 10)

Question 9

Use reduce to sum elements in array

Answer 9

arr.reduce((accumulator, currentValue) => accumulator + currentValue, 0)

Question 10

Find first element in array using find

Answer 10

arr.find(element => element > 10)

Question 11

Find if an element in array satisfies condition

Answer 11

arr.some(element => element > 10)

Question 12

Find if an element in array satisfies condition

Answer 12

arr.some(element => element > 10)

Question 13

Find if every element in an array satisfies a condition

Answer 13

arr.every(element => element > 10)

Question 14

Merge two arrays

Answer 14

arr1.concat(arr2)

Question 15

See if array includes a value

Answer 15

arr.includes(element)

Question 16

Join array into string

Answer 16

arr.join(separator)

Question 17

Sort array of strings

Answer 17

arr.sort()

Question 18

Sort array of numbers

Answer 18

numbers.sort((a,b) => a-b)

Question 19

Loop through values using for each

Answer 19

words.forEach(word => {
console.log(word)
}