What is JavaScript?

A client-side scripting language that is interpreted and executed on the web browser to enable dynamic and interactive content like search suggestions, countdown timers and animations. JavaScript is also the foundation for modern front-end frameworks like React and Vue.

A standardized programming language developed by Ecma International (formerly the European Association for Standardizing Information and Communication Systems) to deliver an open source, unified platform-independent programming language that behaves the same way across applications that support it. It’s based on Java but allows for more flexible and expressive code. It is a general-purpose, object-oriented and imperative programming language with a strong focus on code readability.

It is a powerful, robust and scalable programming language designed to provide functionality to websites and web applications. Originally written for Netscape Navigator in 1995, it is now used by most major web browsers and is widely used for adding interaction elements to websites and apps.

JavaScript is an interpreted language meaning it is executed line by line and that it can execute commands from the user’s keyboard in addition to mouse or touch input. It can work with multiple windows and tabs and can even work offline. It is also cross-platform and can run on both desktop computers and mobile devices.

As a general-purpose, object-oriented, and imperative programming language, JavaScript supports a wide range of data structures and operations. These include variables, functions, conditional statements, looping and iteration, recursion, typing and type checking, arrays, lists, and maps. It can also perform arithmetic operations and logic and can create string literals. It also provides support for object orientation and encapsulation.

Variables are a fundamental part of the JavaScript language and a key feature for storing data that can be reused throughout a program. They can store data of any type, but they must be given a unique name with specific syntax to ensure that they are correctly identified and accessed. For example, a variable named “carName” must be a valid car model number or it will not be recognized. Similarly, a variable named “myVariable” must be an actual value, or it will not be correctly processed.

Other important data types in JavaScript are numbers, strings and objects. All of these data types are stored in variables, and each has a different set of rules for how they are handled. For instance, a string must be enclosed in double quote marks to indicate that it is a string, while numbers and the words true and false don’t require quotes.

When a piece of JavaScript code is entered into the engine it first must be parsed which means that the code is converted to a data structure known as an Abstract Syntax Tree. The AST is then saved for later use. Once it is saved, the engine will evaluate the identifiers in the AST to determine what function should be called and to resolve any ambiguities in the code. This step is required because a machine needs to know what to do with the code before it can be executed.