What Is JavaScript?


JavaScript is a very powerful client-side scripting language that is used to enhance the user experience of a webpage. It is mainly used to make a webpage more lively and interactive with the help of animations and effects. It is also a popular choice for creating mobile and game apps.

It is a dynamic language with a lot of potential and can be used for all kinds of things from building games to adding animations and effects to a website, a mobile app or even in a desktop application. It is widely used in web development, especially in HTML5 websites.

JS is a non-blocking language that does not wait for HTML and CSS to finish before it can do anything on the DOM (Document Object Model) elements. It can work with a variety of different engines, including browser and Node APIs, so it can be very useful for back end web development as well.

A good JS engine will offload long-running tasks to separate threads so they don’t block the main JS thread, which is why it’s called “non-blocking.” This is an advantage of using JavaScript as it means your pages will load faster and you can be sure your site’s performance won’t suffer when a big chunk of your JavaScript code is executed.

JavaScript has a concept called the scope chain that lets the JS engine traverse up and down the execution contexts it’s defined in, looking for functions and variables in them. Only when it can’t resolve a variable in the scope chain does it stop executing and throw an error.

Another important part of a JavaScript engine is the call stack. It works on the Last In First Out (LIFO) principle and manages the creation and deletion of code execution context. This ensures that each function that is called has its own call stack.

A call stack is a data structure that stores local variables, functions, and objects of those functions. It also has a reference to a memory address in the memory heap where these are stored.

It is a very good idea to use a call stack when developing your own code so that you know where everything is at any given time. It will make it easier to understand where you are in the execution context and what you’re doing.

The call stack also helps keep track of which functions are being called at any given time, allowing you to quickly identify where the function is that needs to be run. This will speed up your code writing and reduce the risk of errors.

Often the order of function calls is crucial, because it can have an impact on the DOM. Typically, the order of function calls will be based on the order in which they are loaded and parsed by the JS interpreter.

You can control how your scripts are loaded with the async or defer attributes on script> elements, and they will load in a specific order so that you can be sure that your JavaScript code is running in the correct order. This can be a bit tricky to get right, but it’s worth doing so to ensure that your scripts run in the correct order without blocking the page or causing other problems.