Using the length of an array

01 / 04

Writing the number by hand is risky

So far you have written the count yourself, as in i < 3.

The trouble is that you forget to fix it when you add an item later. Miss it and the last one never gets handled — a bug that is very hard to notice.

02 / 04

.length tells you the number

Write .length after an array and you get how many items are in it right now.

Counting becomes the array's job rather than yours.

const fruits = ["apple", "orange", "peach"];console.log(fruits.length);

Result

03 / 04

Use it in the loop condition

Swap the 3 in i < 3 for fruits.length and you get a repetition that runs correctly however many items there are.

This is the finished form for pairing for with an array. You will write it many times.

const fruits = ["apple", "orange", "peach", "pear"];for (let i = 0; i < fruits.length; i++) {  console.log(fruits[i]);}

Result

apple
orange
peach
pear

04 / 04

The last item is length - 1

Because numbering starts at 0, the last number is one less than length.

Three items means length is 3 and the last number is 2. Write list[list.length - 1] and you get the last item whatever the length.

const list = ["a", "b", "c"];console.log(list.length);console.log(list[list.length - 1]);

Result

3
c