The Array object, as with arrays in other programming languages, enables storing a collection of multiple items under a single variable name, and has members for performing common array operations.
In JavaScript, arrays aren't primitives but are instead Array objects with the following core characteristics:
JavaScript arrays are resizable and can contain a mix of different data types. (When those characteristics are undesirable, use typed arrays instead.)
JavaScript arrays are not associative arrays and so, array elements cannot be accessed using arbitrary strings as indexes, but must be accessed using nonnegative integers (or their respective string form) as indexes.
JavaScript arrays are zero-indexed: the first element of an array is at index 0, the second is at index 1, and so on — and the last element is at the value of the array's length property minus 1.
JavaScript array-copy operations create shallow copies. (All standard built-in copy operations with any JavaScript objects create shallow copies, rather than deep copies).
In JavaScript, an array is an ordered list of values. Each value, known as an element, is assigned a numeric position in the array called its index. The indexing starts at 0, so the first element is at position 0, the second at position 1, and so on.
Arrays can hold any type of data-such as numbers, strings, objects, or even other arrays-making them a flexible and essential part of JavaScript programming.
Example1:
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:
let car1 = "Saab";
let car2 = "Volvo";
let car3 ="BMW";
However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The solution is an array!
An array can hold many values under a single name, and you can access the values by referring to an index number.
Example2:
1. Create Array using Literal
Creating an array using array literal involves using square brackets [] to define and initialize the array.
// Creating an Empty Array
let a = [];
console.log(a);
// Creating an Array and Initializing with Values
let b = [10, 20, 30];
console.log(b);
2. Create using new Keyword (Constructor)
The "Array Constructor" refers to a method of creating arrays by invoking the Array constructor function.
// Creating and Initializing an array with values
let a = new Array(10, 20, 30);
console.log(a);
Accessing Array Elements
You access an array element by referring to the index number:
const cars = ["Saab", "Volvo", "BMW"];
let car = cars[0]
Changing an Array Element
This statement changes the value of the first element in cars:
cars[0] = "Opel";
const cars = ["Saab", "Volvo", "BMW"];
cars[0] = "Opel";
Arrays are Objects
Arrays are a special type of objects. The typeof operator in JavaScript returns "object" for arrays.
But, JavaScript arrays are best described as arrays.
Arrays use numbers to access its "elements". In this example, person[0] returns John:
// Array
const person = ["John", "Doe", 46]
// Object
const person = {firstName:"John", lastName:"Doe", age:46};
References:
https://www.w3schools.com/js/js_arrays.asp
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
https://www.geeksforgeeks.org/javascript/javascript-arrays/
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