Javascript, originally called LiveScript, is a programming language created by Netscape and was born in 1995 with a very clear purpose: to improve user navigation directly from the browser.

Javascript is the third building block of front-end web development, along with HTML and CSS. Each of these three languages has a very specific function in web development:

• HTML is used to form the skeleton and structure of a web page’s content.
• CSS defines the style and appearance of the web.
• Javascript breaks with the staticity of HTML and allows the creation of dynamic and interactive elements, greatly improving the interaction of users with a web page.

Therefore, to become a professional web developer you need development skills in these three languages broad enough to carry out a complete frontend project.

Although later we will see in depth the features of this powerful language, it should be noted that it is a language that runs on the client side (browser) and that its wide use in web pages and other applications has placed Javascript as one of the most demanded programming languages in recent years.

Javascript Features

Client-side language:

When we say that a language is client-side, we mean that it runs on the client’s own machine through a browser. Some of these languages are javascript itself, HTML, CSS, or Java.

This category of languages differs from the other major category: server-side languages. These languages are executed and interpreted by the server itself and need to be processed before being displayed to the end user. Some of the best-known server-side programming languages are PHP, ASP, and PERL.

Object-oriented language:

JavaScript is an object-oriented language. That a language is object-oriented means that it uses classes and objects as structures that allow it to be organized in a simple way and are reusable throughout development. Other object-oriented languages are Java, Python, or C++.

Weakly typed or untyped:

That a language is weakly typed means that it is not necessary to specify the data type when declaring a variable. This feature is a great advantage when it comes to programming speed, but it can cause us to make more errors than if we had this restriction that strongly typed languages such as C++ or Java have.

High-level:

Javascript being a high-level language means that its syntax is easily understandable because of its similarity to the language of people. It is called “high-level” because its syntax is far from the machine level, that is, the code that a computer processes to execute what we program.

A high-level language such as Javascript allows its entry barrier and learning curve to be drastically shortened. An example could be that the conditional statement begins with “IF” which means “if…” in English, allowing one to quickly associate its operation and meaning. Another widely used high-level language and one of the best to get started in programming because of this feature is Python.

Interpreted language:

JavaScript is an interpreted language because it uses an interpreter that allows lines of code to be converted into machine language. This has a number of advantages such as the reduction of processing on web servers by running directly in the user’s browser, or that it is suitable for multiple platforms allowing the same code to be used.

In addition to JS, other examples of interpreted languages are C#, Ruby, Java, and Python.

Widely used by developers:

When choosing whether or not to learn a new language, it is not only necessary to find out about the type of language or its learning curve, but also its demand in the market. Javascript is currently one of the most demanded languages in recent years due to its versatility and its infinite capacity to create increasingly attractive platforms.

According to a study of requirements requested in job offers in 2020 conducted by Boston Northeastern University, Javascript is the second most demanded language only behind Python.

Javascript Libraries:

Javascript has a wide repertoire of libraries for various functionalities thanks to its large development community. Below, we include some of the most used libraries or frameworks in the market and their main features:

jQuery

The jQuery library is one of the most popular libraries for programming in javascript and has a large community of users and developers. One of its main features is that it is an open-source library, that is to say, open source. The philosophy of jQuery is based on making simple and concise coding commands, programming in one or two lines which in javascript would take 20 lines. This feature greatly simplifies the development work, making it very popular in the industry.

In addition, this library has a large number of extensions or plugins that allow you to add more features to the core, giving the developer great flexibility and capabilities when dealing with a javascript project. Important companies such as Google, WordPress, and IBM rely on jQuery for several of their projects.

React

Along with jQuery, React JS is another key JavaScript library for web developers. React was created by Facebook in 2011 and explicitly planned to build dynamic, fast, and interactive user interfaces. Like jQuery, it is also an open-source library focused on the frontend part of an application.

It has gained great popularity in the industry because less code is needed than using javascript alone, and its performance and functionality are excellent. In addition, its use of VirtualDOM allows for speeding up the update process, since it only affects the modified components and does not update all the components as in conventional development.