Map

Question 1

Initialise a map

Answer 1

const map = new Map()

Question 2

Add or update a key-value pair in a map

Answer 2

map.set(key, value)

Question 3

Retrieve a value from the map using a key

Answer 3

const value = map.get(key)

Question 4

Determine if a map contains a specific key

Answer 4

const hasKey = map.has(key)

Question 5

Remove a key-value pair from the map

Answer 5

map.delete(key)

Question 6

Loop through key-value pairs in a map

Answer 6

for (const [key, value] of map) {
console.log(key, value)
}

Question 7

Convert map to array

Answer 7

const entries = Array.from(map.entries())

Question 8

Filter map values based on a condition

Answer 8

Array.from(map.values()).filter(value => condition)

Question 9

Remove all key-value pairs from map

Answer 9

map.clear()

Question 10

Get key value pairs for map

Answer 10

myMap.entries

Get array:
Array.from(myMap.entries())

Question 11

Create array of key values from map and map those values

Answer 11

Array.from(myMap.entries()).map(([id, borrower]) => ({
book: this.checkBookExists(id),
borrower,
}));