Arrays in 

Ahmed Murtaza 😎

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It is a data structure consisting of a collection of elements, Each identified by at least one array index or key

Applications of Array

Array of Donuts

Array of links, icons and thumbnails

Array of links, icons and thumbnails

Declaration

let arr = new Array(1,2,3);

let arr = Array(1,2,3);

let arr = [1,2,3];

In most languages, the elements of an array required to be of same type. JavaScript allows an array to contain any type of values:

var arr = [  'string', 42.0, true, false, null,      
    undefined,  ['sub', 'array'], 
    {object: true}, NaN
];

Accessing & Assigning in Array

var arr = [27,"Karachi",true];
arr[0]; // 27
var arr = [27,"Karachi",true];
arr[3] = 72;

arr; // [27, "Karachi", true, 72]

Accessing

Assigning

.length

var colors = ['Red', 'Blue', 'Yellow']; 
console.log(colors.length); // 3 

var arr = Array(10);  // Creates an array 
//with no element, but with  arr.length set to 10


// The above code is equivalent to
var arr = [];
arr.length = 10;

example

var colors = ['Red', 'Blue', 'Yellow']; 
console.log(colors.length); // 3 

colors.length = 2; 
console.log(colors); // ["Red","Blue"] - Yellow has been removed 

colors.length = 0; 
console.log(colors); // [] the colors array is empty 

colors.length = 3; 
console.log(colors); // [undefined, undefined, undefined]

Iterating Array values

let colors = ['red', 'green', 'blue']; 

for (let i = 0; i < colors.length; i++) {   
   console.log(`Color is ${colors[i]}`); 
}

Array Built-in Methods

concat

pop

push

shift

unshift

.concat()

let myArray = new Array("33", "44", "55");  

myArray = myArray.concat("3", "2", "1"); 

console.log(myArray); // ["33", "44", "55", "3", "2", "1"]

The concat() method joins two arrays and returns a new array:

.pop()

let myArray = new Array("1", "2", "3"); 

let last = myArray.pop(); // "3"

myArray // ["1", "2"]

The pop() method removes the last element from an array and returns that element

.push()

let myArray = new Array("1", "2"); 

myArray.push("3"); // 3

myArray // ["1", "2", "3"]

The push() method adds elements to the end of an array and returns the resulting length of the array

.shift()

let myArray = new Array ("1", "2", "3"); 

let first = myArray.shift(); // "1"

myArray // ["2", "3"]

The shift() method removes the first element from an array and returns that element

.unshift()

let myArray = new Array ("1", "2", "3"); 

myArray.unshift("4", "5"); // 5

myArray // ["4", "5", "1", "2", "3"]

The unshift() add elements to the Front of an array and returns the new length of it

Thank You

ahmedgmurtaza

Array basics in JavaScript

By Ahmed Murtaza

Made with Slides.com

Array basics in JavaScript

overview of Arrays in JavaScript, Array length and other properties, array applications, array methods: reverse, pop,push,shift, unshift, join.

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