JavaScript Arrays

variable is undefined or null

The JavaScript Arrays object is a global object that is used to store multiple values in a single variable.

The JavaScript Arrays object is a global object that is used to store multiple values in a single variable i.e. collection of elements.

Syntax:

var cars = [
"Fiat",
"BMW",
"Nissan"
];

Note: Never put a comma after the last element (like “Nissan”,). This can be effected is inconsistent across different browsers.

Using keyword new:

var cars = new Array("Fiat", "BMW", "Nissan");

Use [] instead because, there is no need to use the JavaScript’s new Array().

Read Also: Detect Browser in JavaScript

How to access:

By index number, you can an array element.

var firstCar = cars[0];

cars[0] is the first element
cars[1] is the second element
cars[2] is the third element

So, for last element:

var lastCar = cars[cars.length - 1];

Length of an Array:

The length property of an array returns the length of an array.

console.log(cars.length);

Looping an Array:

cars.forEach(function (item, index, array) {
console.log(item, index);
});

Add to the end:

var newArray = cars.push("Innova");

Remove from the end:

var lastArray = cars.pop();

Remove from the front:

var first = cars.shift();

Add to the front:

var newLength = cars.unshift("Alto");

Find the index:

var pos = cars.indexOf("Innova");

Remove an item by Index Position:

var removedItem = cars.splice(pos, 1);

Copy an Array:

var carsCopy = cars.slice();

Recognize an Array:

typeof cars;

The difference between Arrays and Objects is that arrays use numbered indexes whereas objects use named indexes.

Based on United States, Jacob Frazier is a skilled JavaScript developer with over 8 years of experience. He is passionate about change and trying new things, both professionally and personally. He loves startups and is extremely proactive.

One thought on “JavaScript Arrays”

Leave a Reply

Your email address will not be published. Required fields are marked *