ماڈیول 3 · سبق 1 از 4کورس میں 9/32~10 min

ماڈیول اسباق (1/4)

Arrays: ترتیب دی گئی فہرست

An array is an ordered list of values. In JavaScript the elements can be of different types from each other (although in "good" code they tend to be homogeneous). It's written with square brackets:

const colori = ['rosso', 'verde', 'blu'];
const misti = [1, 'due', true, null];
const vuoto = [];

Reading and writing by index

Indices start at 0. The last valid index is array.length - 1.

const colori = ['rosso', 'verde', 'blu'];
colori[0]; // 'rosso'
colori[2]; // 'blu'
colori[99]; // undefined  ← no error, just undefined
colori.length; // 3

colori[1] = 'giallo'; // now colori is ['rosso', 'giallo', 'blu']
colori[colori.length] = 'x'; // manual push, not recommended

Adding and removing elements

The four classic methods (push / pop / unshift / shift) modify the array in place:

const a = [1, 2, 3];
a.push(4); // a = [1, 2, 3, 4],  returns the new length
a.pop(); // a = [1, 2, 3],     returns the removed element (4)
a.unshift(0); // a = [0, 1, 2, 3],  adds at the head
a.shift(); // a = [1, 2, 3],     removes from the head

Including, searching

['rosso', 'verde', 'blu'].includes('verde'); // true
['rosso', 'verde', 'blu'].indexOf('blu'); // 2
['rosso', 'verde', 'blu'].indexOf('giallo'); // -1

Try it

ورزش#js.m3.l1.e1

کوششیں: 0لوڈ ہو رہا ہے…

Given the array `numbers = [10, 20, 30, 40]`, return as the last expression the last element using length.

ایڈیٹر لوڈ ہو رہا ہے…

اشارہ دکھائیں۔

The last valid index is length - 1.

3 کوششوں کے بعد حل دستیاب ہے۔

Review exercise

ورزش#js.m3.l1.e2