In this article we will learn about arrays, first, we learn some fundamental concepts of arrays and then move to some essential array methods.

let's get start

what is an array?

An array is generally described as "list-like objects", they are basically single objects that contain multiple values stored in a list. Array objects can be stored in variables.

An array can hold values of mixed types. For example, you can have an array that stores elements with the types number, string, and boolean.

The size of an array is dynamic and auto-growing. In other words, you don’t need to specify the array size up front. we can access each value inside the arrays individually, To access an element in an array, you specify an index in the square brackets [ ]: arrayName[index]

const names = ["pranit", "ingole", " mayur", "yachi" , 1, true];

console.log(names[0]) // pranit 
console.log(names[2]) // mayur
console.log(names[3]) // yachi
console.log(names[4]) //1
console.log(names[5]) //true

Efficient things with the array, like loop through it and do the same thing to every value. Maybe we've got a series of product items and their prices stored in an array, and we want to loop through them all and print them out on an invoice while totaling all the prices together and printing out the total price at the bottom.

If we didn't have arrays, we'd have to store every item in a separate variable, then call the code that does the printing and adding separately for each item. This would be much longer to write out, less efficient, and more error-prone. If we had 10 items to add to the invoice it would already be annoying, but what about 100 items, or 1000? ya, that's why we have an array.

you should know before the move

• primitive-vs-reference-data-types-in-javascript

• Mutable and Immutable in js

  About let const var with primitive and non-primitive data type

Create an Array

There are two ways to create a arrays

first way

const names = ["pranit", "ingole", " mayur", "yachi" , 1, true];

// with const we need to declare and initialization simultaneously at first
// we can't reassign it with another variable

another one

You can also create an array using JavaScript's new keyword.

const myarray = new Array(1, 2, 3);

Note creating an array with new keywords not recommended

Now time start learning about the array of methods

• length property

you can find out the length of the array with the length property

const mycollegeFriends = ["Harsh", "Mayur", "Abhay"];

 console.log(mycollegeFriends.length) //3

console.log(mycollegeFriends[mycollegeFriends.length - 1])
 //last element// Abhay

Note in javascript primitive value immutable, only reference types are mutable for eg Array in js that's why we are able to change the array element by indexing just one condition, we can't reassign. array with const variable.

• push() Method

push method we used to push the element or elements in the array

const mycollegeFriends = ["Harsh", "Mayur", "Abhay", "yachi"];
mycollegeFriends.push("Aryan", "Nikhil");
console.log(mycollegeFriends); 

output -> ['Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil']


// push method also return current length of array
  const newfriendlistlength =  mycollegeFriends.push("Aryan", "Nikhil");

console.log(newfriendlistlength) //  6

• unshift() Method

  The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.

 const  mycollegeFriends = ['Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil'];
 const some = mycollegeFriends.unshift("Bhushan"); 

 console.log(mycollegeFriends) 
// ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil', 'Aryan', 'Nikhil'];

 console.log(some)// 9 // just like push , unshift also return length of array

• pop() method

The pop() method removes the last element from an array and returns that element. This method changes the length of the array.

const mycollegeFriends = ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil'];
const popped = mycollegeFriends.pop();
console.log(mycollegeFriends);// ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan']
console.log(popped);// Nikhil // It will return pop element

• shift() method

The shift() method removes the first element from an array and returns that removed element. This method changes the length of the array.

const mycollegeFriends = ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil'];

const fromfront = mycollegeFriends.shift();
console.log(mycollegeFriends);// ['Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan']
console.log(fromfront);// Bhushan // It will return element from front

• indexof() method

The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.

const mycollegeFriends = ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil'];
console.log(mycollegeFriends.indexOf("yachi"));// 4 // it will return index number of element

 // what about those element not present and you try to used indexOf() method  to find index number..........

console.log(mycollegeFriends.indexOf("Anurag"));// -1// because i try find index which not present in array

• includes() method

The includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.

const mycollegeFriends = ['Bhushan', 'Harsh', 'Mayur', 'Abhay', 'yachi', 'Aryan', 'Nikhil'];
mycollegeFriends.push(17);
console.log(mycollegeFriends.includes("Mayur")); //true
console.log(mycollegeFriends.includes("Bhushan")); //true
console.log(mycollegeFriends.includes("bhushan")); //flase // beacuse not same elemnt 
console.log(mycollegeFriends.includes("44")); //false
console.log(mycollegeFriends.includes("17")); //flase
console.log(mycollegeFriends.includes(17)); // true

if (mycollegeFriends.includes("Mayur")) {
    console.log("you have call from mayur");
};
// you have call from mayur