JavaScript is a powerful programming language used to create dynamic web pages that can display 2D/3D graphics, animations, and real-time content updates. It is most commonly used for front end web development, but it can also be implemented on the back end as well.
The origins of javascript
A computer scientist at Netscape, Brendan Eich created a scripting language in 1995 that would make interactive web pages possible. It took him only 10 days to develop the first version of the language, but it revolutionized the way we see and interact with information online.
It was originally designed to add a minimal amount of interaction to static web pages, but its versatility and ease of use have allowed it to become the go-to scripting language for creating dynamic and engaging websites. Today, it is used by a huge range of organizations to make static information come to life with pop-up videos, animated images, and real-time updates.
Unlike other languages, it is an extremely efficient client-side scripting language, meaning that it runs directly on the user’s machine instead of sending data to a server. This helps speed up the loading of a page, as the browser isn’t waiting for the code to be processed by the server before displaying it.
The simplest way to load a JavaScript script is by embedding it in the head> section of an HTML document or by referencing it via a.js file that contains the scripting code. The JS code is then sent to the browser and executed alongside the HTML and CSS on the visitor’s machine, creating a functional page displayed in the browser tab.
You can also use a scripting framework, which provides a set of prewritten code that you can reuse to reduce the time and effort required to develop complex applications. These frameworks usually include collections of code libraries that you can repurpose to speed up the development process while reducing errors and scaling up to multiple devices.
Functions and Events
One of the most useful functions in a programming language is a function, which is a self-contained block of code that performs a specific task. For example, a function can extract characters from a string, output a new string with those characters, or calculate the temperature of a certain number of degrees.
Another useful function is an event listener, which is a piece of code that detects when something happens and responds accordingly. For example, a function can check to see if a button is clicked on the page and then call the relevant JavaScript code.
It is important to understand that the JavaScript runtime consists of 2 main components: an event loop and a callback queue. The event loop is responsible for executing your code when the browser encounters an event, while the callback queue is where the browser will wait to receive a response from your code before proceeding with the next element.
The most common type of scripting in a web browser is called asynchronous, which means that it runs on the client’s machine rather than sending the script to the server before running it. Asynchronous programs typically run in the background, while a user is doing something else on the web page. For example, a search engine uses asynchronous functions to communicate with a remote server and return search suggestions. This saves users the hassle of reloading their web page every time they click on a link or change their search terms.