Array_Methods

Question 1

array.length

Question 2

array[0]

Answer 2

find item in array. this way you can also modify item in array eg: array[0] = “hans”.

Question 3

array.indexOf(“item”)

Answer 3

returns index of item

Question 4

array.push(“item”)

Answer 4

add item to end of array

Question 5

array.pop()

Answer 5

removes item at end of array

Question 6

array.unshift(“item”)

Answer 6

add item to beginning of array

Question 7

array(shift)

Answer 7

removes item from beginning of array

Question 8

array.splice(1, 3)

Answer 8

removes item(s) from array, whereby first argument says at which index to start removing and second argument is number of items to remove.

Question 9

for (const item of items) {
}

Question 10

array.map(function)

Answer 10

function double(number) {
return number * 2;
}
const numbers = [5, 2, 7, 6];
const doubled = numbers.map(double);
console.log(doubled); // [ 10, 4, 14, 12 ]

Question 11

array.filter(function)

Answer 11

function isLong(city) {
return city.length > 8;
}
const cities = [“London”, “Liverpool”, “Totnes”, “Edinburgh”];
const longer = cities.filter(isLong);
console.log(longer); // [ “Liverpool”, “Edinburgh” ]

Question 12

string.split(“,”)

Answer 12

create array from string splitting by “,”.

const data = “Manchester,London,Liverpool,Birmingham,Leeds,Carlisle”;

const cities = data.split(“,”);

console.log(cities)
//[“Manchester”, “London”, “Liverpool”, “Birmingham” , “Leeds”, “Carlisle”]

Question 13

array.join(“,”)

Answer 13

converts array to string using , as separator.