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const cars = ["Saab", "Volvo", "BMW"];An Array is an object type designed for storing data collections. Key characteristics of JavaScript arrays are:
: An array is a list of values, known as elements.
: Array elements are ordered based on their index.
: 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 (numbers, strings, objects and other arrays).
If you have a list of items (a list of car names, for example), storing the names 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.
Using an array literal is the easiest way to create a JavaScript Array.
const array_name
= [
item1, item2, ...];
It is a common practice to declare arrays with the const keyword.Learn more about const with arrays in the chapter: JS Array Const.
const cars = ["Saab", "Volvo", "BMW"];Spaces and line breaks are not important. A declaration can span multiple lines:
const cars = [
"Saab",
"Volvo",
"BMW"
];You can also create an empty array, and provide elements later:
const cars = [];
cars[0]= "Saab";
cars[1]= "Volvo";
cars[2]= "BMW";The following example also creates an Array, and assigns values to it:
const cars = new Array("Saab", "Volvo", "BMW");The two examples above do exactly the same. There is no need to use new Array(). For simplicity, readability and execution speed, use the array literal method.
You access an array element by referring to the index number
const cars = ["Saab", "Volvo", "BMW"];
let car = cars[0];Array indexes start with 0. [0] is the first element. [1] is the second element.
This statement changes the value of the first element in cars
cars[0] = "Opel";const cars = ["Saab", "Volvo", "BMW"];
cars[0] = "Opel";converts an array to a string of (comma separated) array values.
const fruits = ["Banana", "Orange", "Apple", "Mango"];
document.getElementById("demo").innerHTML = fruits.toString();Banana,Orange,Apple,Mango
With JavaScript, the full array can be accessed by referring to the array name:
const cars = ["Saab", "Volvo", "BMW"];
document.getElementById("demo").innerHTML = cars;