Getting Started With JavaScript


JavaScript is among the world’s most popular languages, and it powers most of the web pages you see. It’s a scripting language that makes web pages interactive, giving them the ability to perform tasks like filling out forms or scrolling through maps.

A key feature of JavaScript is its ability to run within web browsers without the need for extra programs and compilers. Instead, JavaScript programs are provided directly in a web page’s HTML code and execute automatically when the web browser loads the page.

It’s a flexible and accessible programming language that empowers developers to create complex, dynamic interactive websites and browser games. It can also connect servers and web applications to one another.

The language is based on a tree-like model that allows for easy navigation. It can be used on the client and server side of a web application, and it supports multiple platforms and device types.

Almost every modern web browser has built-in engines that can read and render JavaScript codes. This engine parses the code, creating an Abstract Syntax Tree before converting it to machine-readable code and submitting it for execution.

This process can take a long time, however, so it’s important to use non-blocking JS functions whenever possible. In addition, most engines like V8 allow you to use Event Loops to offload tasks to separate threads and enqueue callbacks in order to keep the main JS thread free to do other things.

In addition, most modern browsers support a feature called “asynchronous” loading, which means that scripts don’t run in the order they are loaded into the DOM. This can be useful if your script> elements aren’t in the right position yet or if they need to wait for other script> elements and the DOM to load before running.

To get started with a simple JS program, you’ll need to define a few basic data types and variables. Variables are containers that hold values of a particular data type and can be passed to other functions or used as parameters.

You’ll also need to understand how to define functions, which are blocks of self-contained code that can be used to perform a specific task. You can use functions to do anything from extracting characters from a string to transforming images.

Understanding how to define functions is essential if you’re planning to use JavaScript for your next project. Functions are defined by putting them in a special block of code, and they contain a single statement that returns the value of whatever it’s called on.

A function can be any number of lines long, and it’s possible to extend a function by adding more lines. This extends the function’s scope, which allows you to include other lines in the function’s execution path.

In addition to defining functions, you can also define closures and lambdas, which are similar to functions except they can be repeated. A closure is a method that lets you create a new function from an existing one. A lambda is an object that you can pass into a function to make it execute the same code as the original function.