What is JavaScript?

If you are a web developer, then chances are you’ve come across javascript, or at least heard of it. Chances are you probably also know that it’s the engine that makes the Internet run. It’s a dynamic language that was created to make the world wide web come alive. It enables things like interactive image galleries, file upload forms, and menu animations and fades. Without it, websites would be static pages of text and images. In fact, even modern browsers wouldn’t function properly without javascript.

Web browsers run JavaScript by invoking a special engine that translates the script to 0’s and 1’s for execution on your computer. These engines contain a call stack and a heap, where code snippets are loaded and executed. Once loaded, the engine parses the code into a data structure known as an abstract syntax tree (AST), and then turns it into machine instructions that can be executed by your computer’s processor. These instructions are then placed on the call stack and executed.

The main goal of javascript is to provide a mechanism to interact with user input, such as mouse clicks, scrolls, and keyboard presses. It also enables you to store and retrieve data, such as your browsing history and webpage preferences. It’s the backbone of many other technologies, including HTML and CSS, making it one of the most widely used languages in the world.

Scripts written in javascript are known as scripts and are embedded right into the HTML of a website or web app. They don’t need any special preparation or compilation to run. They are also single-threaded, meaning only one instruction is executed at a time. This means it’s important to plan your code so that multiple functions can be executed in parallel if needed.

This is where frameworks and libraries like jQuery become your best friend. These libraries contain prewritten code snippets that you can use to add features to your website or app. For example, if you want to add an animation to a navigation bar, you can easily do it by using a jQuery library. There are plenty of other snippets that let you do other fancy stuff with your site.

JavaScript has a number of advanced features, some of which are not found in other programming languages. For example, JS is a dynamically-weakly-typed language, which means you don’t annotate variables with their true types (like string or int) and the type of the variable is determined at runtime. It also has a feature called prototypal inheritance, which allows objects to inherit behavior from other objects.

Another important feature is the Event Loop, which is a queue that offloads long-running tasks from the single JS thread to other threads in your system. This allows your JS program to keep running while the task is being processed, rather than waiting for it to finish before continuing. This is one of the reasons that javascript is considered non-blocking.