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What Is JavaScript?

Learn more about one of the world’s most popular programming languages.

What Is JavaScript

JavaScript is a scripting language that helps websites come to life. JavaScript is one of the most popular programming languages on both the front and back end and it helps Developers in creating web products that are interactive, engaging, and user-friendly. Where HTML and CSS give websites their style and structure, JavaScript makes websites programmable, turning them into rich interactive applications. The JavaScript language is now used by nearly 98 percent of all web pages as a client-side programming language.

Intro to JavaScript

JavaScript is a dynamic programming language used by Developers to add complex features and content on web pages like animated graphics, interactive maps, scrolling multimedia playlists, and more.

Developers write JavaScript code right into a web page’s HTML and it runs automatically as a page loads. JavaScript can be used to change HTML content, change HTML attribute values, change HTML styles (CSS), and to hide or show HTML elements. The simplest way to understand what JavaScript is might be to imagine the Internet without it: pages would feel static and lifeless.

Every time you see an embedded YouTube video or a Twitter feed that automatically refreshes, you’re seeing JavaScript in action.

JavaScript syntax is based on the C programming language and supports object-oriented programming with object prototypes (rather than classes) as well as functional programming. JavaScript programs manipulate values, which belong to the following types:

  • Number
  • BigInt
  • String
  • Boolean
  • Function
  • Object
  • Symbol

JavaScript History

The history of JavaScript begins in 1995 when it was invented by Netscape programmer Brendan Eich. Originally known as “Mocha” and then “LiveScript” when it was first shipped, JavaScript was then renamed as part of an ill-advised decision to capitalize on the popularity of the Java programming language, even though the programming languages were entirely different.

Web Developers had their intro to JavaScript during the browser wars when Microsoft’s Internet Explorer and Netscape’s Navigator were in tight competition. Amid that environment, Microsoft designed something similar to JavaScript called JScript in 1996, which became the industry standard for client-side scripting for years as Internet Explorer held a huge market share.

Months after the introduction of JScript, Netscape submitted JavaScript to the international standards organization ECMA International, resulting in the first version of the ECMAScript standard in 1997. The standard received a significant update as ECMAScript Edition 3 in 1999.

Many parts of the fourth edition, which was abandoned due to disagreements over its complexity, formed the basis of 2009’s ECMAScript edition 5, which was a huge success. It was released in 2009, and by 2013, all major browsers — Internet Explorer included — were in full compliance.

JavaScript’s rise coincided with the introduction of the Firefox browser from Netscape’s successor, Mozilla, in 2004, the debut release of Google’s Chrome browser in 2008 (along with Google’s release of what remains one of the most powerful JavaScript engines, V8), and the introduction of large and popular JavaScript frameworks and libraries such as jQuery, Prototype and Dojo Toolkit.

The ambitious sixth major edition of the standard, called ES6 and codenamed “Harmony,” was released in 2015. Like ES5, it was a major success and all major browsers were in full compliance by spring 2017.

Difference Between Java and JavaScript

The difference between Java and JavaScript is significant despite their similar names, as the two coding languages are written differently, require different plug-ins, and have vastly different applications and uses. If you’re curious what is the difference between Java and JavaScript, here is a breakdown of the similarities and differences:

Java and Javascript Similarities

Some of the major areas where Java and JavaScript are similar includes:

  • Object-oriented programming. For both languages, a Web Developer needs to understand object-oriented programming and how to code objects based on their contextual relationships. Although even here, there is an important difference between Java and JavaScript. JavaScript doesn’t distinguish objects based on types, while in Java, objects are divided into classes and instances with all inheritance through the class hierarchy. Java is an OOP language while JavaScript is an object-based scripting language.
  • Browser compatibility. Java and JavaScript can both be run in a browser. All modern web browsers support JavaScript, while Java Applets can also run in a browser, though not without potential security and compatibility complications that some would rather avoid.
  • Back-end applications. The two languages both have a range of server-side uses. Java, in particular, is crucial and used a lot for back-end development, powering technologies like JBoss, Apache, and WebSphere. And although JavaScript is typically used more often for writing client-side scripts and apps, Node.js has allowed JavaScript to be run not only on web browsers but also on the server.

Java and JavaScript Differences

Although they do have some elements in common, there are many Java and JavaScript differences including:

  • Complexity: Because Java’s strong type checking and class inheritance requires tightly coupled object hierarchies, programming with Java is a bit more complicated and less user-friendly than JavaScript. By comparison, JavaScript offers more freedom, and a Developer writing JavaScript does not need to declare all classes, variables, and methods, and JavaScript variables, function return types, and parameters don’t need to be explicitly typed.
  • Running platform. Where Java applications and programs run in Java virtual machine, JavaScript web applications run in a browser window with no further setup required. Java programs are platform-independent, meaning they can run on any platform that has a JVM installed on it, including desktops, mobile apps, and embedded systems.
  • Compilation. Where JavaScript is a text-based programming language with code written in plain text, Java code must be compiled.
  • Objects. Javascript objects are prototype-based, while Java objects are class-based.

Pros and Cons of JavaScript

The pros and cons of JavaScript include its speed, intuitive nature, and massive popularity on the positive side, balanced by concerns over security.

Advantages of JavaScript

  • Speed Client-side JavaScript can be run within the browser and that typically makes it very fast. Furthermore, major browsers support just in time (JIT) compilation for JavaScript, so the code doesn’t have to be compiled before running it. (A web page with internal JavaScript code will load even faster, compared to pages that have to reference external code.)
  • Popularity. JavaScript is downright ubiquitous in web development and game development. That means that there are a ton of free resources out there to help Developers learn to use JavaScript.
  • Interoperability. JavaScript integrates well with other programming languages and it can be used for a large number of applications.
  • Create products that delight users. JavaScript helps Developers greatly improve the user experience on a site with interactive features, animations, menus, and more. These rich interfaces have become a staple of the modern Internet experience.
  • Intuitive to learn. JavaScript can be a friendly language to learn because it features simple, flexible syntax and code that is easy to write and debug.

Disadvantages of JavaScript

Although they do have some elements in common, there are many Java and JavaScript differences including:

  • Security. JavaScript code is executed on the client-side — on the user’s computer, in other words — and that can make it vulnerable to cross-site scripting and other types of malicious code injection, oftentimes without the user or site owner being aware. As a result, some people disable JavaScript.
  • Must test across different browsers. Different browsers can still interpret JavaScript differently, so for Developers writing JavaScript code, block out some time to test your scripts in all major browsers to ensure all functions work as intended. That said, JavaScript is so popular that any incompatible browsers would not be widely used.
  • Anyone can view your code. JavaScript code is viewable in the browser, so anyone who can visit your site could read — and reuse — your code.

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