What You Need to Know About Javascript

javascript is the language that makes web pages interactive. It is the programming language behind slideshows, music and videos on web pages, and real-time information like stock or crypto prices or product availability on a website. It is also used to create chat widgets, form fields, search boxes, and other web page elements. In fact, you probably use JS without even knowing it–for instance when your Facebook timeline automatically updates on your screen or Google suggests searches as you type.

The main purpose of javascript is to add functionality to HTML pages, making them more responsive and interactive. This is accomplished by using JavaScript to manipulate the document object model (DOM) which is the family tree of HTML elements on a webpage. JS is also event driven which means it can respond to keyboard input and other events that happen on a webpage. It can also run on the server side of a website to access resources and computing power that would be difficult or impossible for a purely client-side application to accomplish.

A few key elements to know about javascript are variables, operators and functions. Variables are containers that hold values of any data type. They are named and referenced with the var keyword in JavaScript. When a variable is not declared, it is considered undefined. This is why it is important to write good code, with clear and descriptive names for variables.

Operators in javascript include , =, >= and . These work for both strings and numbers. The double-equals operator performs type coercion if you try to compare objects of different types, which can produce some interesting results. The triple equals operator does not perform any type coercion and is preferred. Functions are blocks of code that do something, and they are identified with the fn keyword in JavaScript. Functions can take arguments, and these are specified with the arg keyword.

Lastly, javascript offers a few functions that allow you to build reusable pieces of code. The Symbol function, for example, generates unique identifiers that can be used to refer to any type in the language. There are also registered symbols, shared constants, and well-known symbols that are recognized as “protocols” for certain operations in the language.

The fn() and alert() functions are two examples of built-in JavaScript functions. There are many others as well, which can be found in the online javascript documentation.

Another great feature of javascript is its asynchronous nature. The async attribute in a script allows you to fetch and execute a script without blocking the browser while the rest of the page loads. It is best practice to use async when the scripts on a web page have no dependencies on each other and are not required to be executed in any particular order. This will help to improve page load times and user experience. However, there are some caveats to using async. For example, a script that uses async may not work with some older browsers.