JAVASCRIPT: Basics

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An Introduction to JavaScript

JavaScript is one of the most widely used programming languages in web development. It enables dynamic behavior on websites, transforming static HTML and CSS into interactive user experiences.

A Brief History

JavaScript was created in 1995 by Brendan Eich while working at Netscape Communications Corporation. Originally named Mocha, it was later renamed to LiveScript and then finally to JavaScript. Despite its name, JavaScript is not related to Java; the name was chosen due to Java's popularity at the time. JavaScript quickly became a standard for web development and was formally adopted by the European Computer Manufacturers Association (ECMA) as ECMAScript in 1997.

Purposes of JavaScript

JavaScript serves multiple purposes in web development:

Client-Side Interactivity: It allows developers to create interactive web elements such as drop-down menus, form validations, and animations.
Dynamic Content: JavaScript can modify the content of a webpage without requiring a reload, enhancing the user experience.
Server-Side Programming: With environments like Node.js, JavaScript is also used for server-side development.
APIs and Libraries: It enables the use of various APIs and libraries like React, Angular, and Vue.js, which facilitate the development of complex web applications.

An Interpreted Language

Programming languages can generally be categorized as interpreted or compiled:

Interpreted Languages: These languages are executed line-by-line by an interpreter at runtime. JavaScript is an interpreted language, meaning the browser reads and executes the script directly. This allows for quick testing and immediate feedback during development but may be slower in execution compared to compiled languages.
Compiled Languages: These languages are transformed into machine code by a compiler before execution. This process often results in faster execution times since the entire code is translated into a lower-level language that the computer can run directly. Examples of compiled languages include C and C++.

JavaScript is an interpreted langauge.

Including JavaScript in a Web Page

JavaScript can be included in an HTML document using the <script> element. Unless the script is external, it is best to make the script tag the last item in the body, so that all html content loads prior to the script running. Here is an example of a basic web page with script tags:

<!DOCTYPE html>
<html>
<head>
    <title>Inline JavaScript Example</title>
</head>
<body>
    <h1 id='target'>Hello, World!</h1>
    <script>
        document.getElementById('target').innerHTML = 'Hello, JavaScript!';
    </script>
</body>
</html>