{"id":28341,"date":"2022-03-07T10:51:08","date_gmt":"2022-03-07T10:51:08","guid":{"rendered":"https:\/\/www.devopsschool.com\/blog\/?p=28341"},"modified":"2022-12-23T06:48:05","modified_gmt":"2022-12-23T06:48:05","slug":"what-is-javascript-and-how-it-works-an-overview-and-its-use-cases","status":"publish","type":"post","link":"https:\/\/www.devopsschool.com\/blog\/what-is-javascript-and-how-it-works-an-overview-and-its-use-cases\/","title":{"rendered":"What is JavaScript and How it works? An Overview and Its Use Cases"},"content":{"rendered":"\n

What is JavaScript ?<\/h2>\n\n\n\n
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JavaScript is\u00a0a dynamic programming language that’s used for web development, in web applications, for game development, and lots more<\/strong>. It allows you to implement dynamic features on web pages that cannot be done with only HTML and CSS.<\/p>\n\n\n\n

Why it is used?<\/h2>\n\n\n\n

HTML and CSS are languages that give structure and style to web pages, JavaScript gives web pages interactive elements that engage a user.<\/p>\n\n\n\n

History of JavaScript<\/h2>\n\n\n\n

JavaScript was originally developed by Brendan Eich of Netscape Communications Corporation under the name\u00a0Mocha<\/em>, then\u00a0LiveScript<\/em>, and finally renamed to JavaScript. The change of name from LiveScript to JavaScript roughly coincided with Netscape adding support for Java technology in its Netscape Navigator web browser. JavaScript was first introduced and deployed in the Netscape browser version 2.0B3 in December of 1995. When JavaScript was added to Internet Explorer, it had to be officially called “JScript”, because Netscape owns the name “JavaScript”. The choice of name proved to be a source of much confusion.<\/p>\n\n\n\n

The latest version of the language is ECMAScript 2018 which was released in June 2018.<\/p>\n\n\n\n

How Does JavaScript Work?<\/h2>\n\n\n\n

There are two important pieces to learn about: How the web browser works, and the Document Object Model (DOM).<\/p>\n\n\n\n

The web browser loads a web page, parses the HTML, and creates what is known as a Document Object Model (DOM) from the contents. The DOM presents a live view of the web page to your JavaScript code.<\/p>\n\n\n\n

The browser will then grab everything linked to the HTML, like images and CSS files. The CSS information comes from the CSS parser.<\/p>\n\n\n\n

The HTML and CSS are put together by the DOM to create the web page first. Then, the browsers’ JavaScript engine loads JavaScript files and inline code but does not run the code immediately. It waits for the HTML and CSS to finish loading.<\/p>\n\n\n\n

Once this is done, the JavaScript is executed in the order the code is written. This results in the DOM being updated by JavaScript code and rendered by the browser.<\/p>\n\n\n\n

The order here is important. If the JavaScript did not wait for the HTML and CSS to finish, it would not be able to change the DOM elements.<\/p>\n\n\n\n

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