What Is JavaScript?

Along with hypertext markup language (HTML) and cascading style sheets (CSS), javascript is the backbone of web development. It’s used to make websites dynamic and interactive. It also allows for real-time data updates in browsers and powers chat applications like WhatsApp, as well as online collaboration tools and browser-based multiplayer games.

JavaScript is a lightweight interpreted programming language. This means that the code is interpreted by the browser at run time, rather than compiled into a binary format ahead of time as in traditional compiled languages like C or Java. However, this doesn’t mean that it runs slowly; a technique called just-in-time compilation improves performance by automatically converting the source code into a faster binarized version while the script is being executed.

The core language features of javascript are its scope, variables, and functions. Functions are a fundamental part of any programming language and javascript is no exception. A function can take any number of parameters, and can declare variables inside of its body that are specific to that function. The function can also return a value that will terminate the function and return control to the caller.

During the execution phase, a variable in javascript will be assigned a value by the engine. The identifiers of variables are stored in the Variable Object, and a list of their current values is kept in the Scope Chain. Each variable has a type, which is determined during the declaration stage. If the variable is declared using let or const, it cannot be reassigned to a different type, but it can still be changed.

javascript provides several math operators, including +, -, *, /, and % (remainder and exponentiation). It also includes Boolean values true and false and the Symbol type for creating unique identifiers that won’t clash with other symbols in the program. Other key functions include res, which can return an array of values from a map or recursively call a function with each iteration.

In addition to its native capabilities, javascript can also communicate with other software over the internet, known as APIs (Application Programming Interfaces). Web page designers use javascript to interact with these remote APIs to perform tasks, such as validating the information that users enter into web forms.

There are many ways to start learning javascript, but the easiest is to use a browser that supports javascript, such as Chrome. To open the browser’s console, click the menu icon (3 dots) on the top right of the browser and select More Tools > Developer Tools or press Control+Shift+J on Windows or Command+Shift+J on Mac. Then, either type a javascript command into the console log or paste in a snippet of javascript and press enter to run it. Once the console log is cleared, you can then close it and go back to your website. This is how most developers start their coding journey, and this is a good way to get started because it will help you understand the syntax and structure of javascript.