JS Arrays

What is an Array?

• An array is a collection of multiple values stored in a single variable.
• It is an Object type.
• List of values known as element.
• The first element is at index 0, the second at index 1, and so on.
• Arrays can grow or shrink as elements are added or removed.
• Arrays can store elements of different data types. So it is Heterogeneous.

Why use Array?

• Instead of declaring dozens of separate variables for related items (like car1, car2, etc.), they can be grouped into one array.
• Unlike in many other languages, JavaScript arrays are resizable and can hold a mix of different data types.
• Arrays make it easy to loop through thousands of items to perform bulk operations.

Creating an Array:

const fruits = ["apple","orange","banan"]

//You can also create an empty array, and provide elements later:

const fruits = [];

fruits[0] = "Apple";
fruits[1] = "Orange";
fruits[2] = "Banana";

//The following example also creates an Array, and assigns values to it:

const fruits = new Array("Apple", "Orange", "Banana");

Accessing Array Elements:

document.write(fruits[0]);
document.write("<br>")
document.write(fruits[1]);

Loop through Array :

Normal :

for(let i =0; i<fruits.length; i++){
    document.write(fruits[i]);
    document.write("<br>");
}

Output:

apple
orange
banan

Using for of :

for(let a of fruits)
{
    document.write(a);
    document.write("<br>");
}

Using forEach :

fruits.forEach(a=> 
{
    document.write(a);
    document.write("<br>");

}
);

----------------------

const numbers = [1,2,3,4,5];

let sum = 0;
numbers.forEach(a=> sum=sum+a);
document.write(sum);

Updating value:

const fruits = ["apple","orange","banan"]

document.write(fruits);
fruits[1] = "grapes";
document.write(fruits);


Output :

apple,orange,banan
apple,grapes,banan

Array Length:

const fruits = ["apple","orange","banan"]

document.write(fruits.length);

Output : 3

pop() :

• The pop() method removes the last element from an array.

const fruits = ["apple","orange","banan"]

document.write(fruits);
document.write("<br>");
fruits.pop();
document.write(fruits);

Output :

apple,orange,banan
apple,orange

push() :

• The push() method adds a new element to an array at the end.

const fruits = ["apple","orange","banan"]

document.write(fruits);
document.write("<br>");
fruits.push("papaya");
document.write(fruits);

Output :
apple,orange,banan
apple,orange,banan,papaya