JavaScript Programming

JavaScript is a scripting language designed to add interactivity to HTML pages.  It is an interpreted language (which means that scripts execute without preliminary compilation), and is usually embedded directly into HTML pages.

JavaScript, originally created by Netscape, is a language that’s now supported by every major browser on the market (including Firefox, Chrome, Internet Explorer, Safari, and Opera) and many mobile browsers as well. The JavaScript language is completely devoted to creating Web Applications: applications that run in your browser as part of a web page. Because it can be used to create  interactive web pages, communicate with web services, and create cookies, it is the most popular scripting language on the  web. Browser makers have put a great deal of effort into improving the speed of JavaScript so it runs a lot faster than it did just a few years ago. That means you can now do more computation in a web page, enabling web applications like drawing programs and free poker games.

JavaScript is an Object-Based language; it uses many of the concepts of object-oriented programming, but  it’s not completely object-oriented.

JavaScript gives you, the programmer, more control over web pages. JavaScript uses the document as an environment where you can run applications.

Note: JavaScript is not Java! Java is a object-oriented, compiled language derived from C++. For detailed information on Java, and Java-related courses at O’Reilly School of Technology, see Java Programming.

Where It Fits

JavaScript is an essential part of most web developers’ tool kits. If you plan to do anything based on user interaction with your web pages, you will sooner or later need (and want!) to know JavaScript.


JavaScript was originally developed at Netscape, in the 1990s, as a lightweight, interpreted language suitable for nonprofessional programmers.  It very quickly gained widespread success as a client-side scripting language for web pages. JavaScript has become one of the most popular programming languages on the web.

Example of Usage

JavaScript code is typically embedded within
// <!–[CDATA[
tags in an HTML document, either with the entire code included within the tags, or a link to an external JavaScript (.js) file. Here’s an example of JavaScript code that computes a value and displays it in an alert box:



  var age = 10; 
  var ageInDogYears = age * 7; 
  alert("Age in dog years: " + ageInDogYears); 
// ]]>

Real-World Uses

JavaScript may be used for online games, web pages with computations, animation, validating form inputs, and transmitting information about the user’s reading habits and browsing activities to various websites; for example, for web analytics or page personalization.

JavaScript at the O’Reilly School of Technology

JavaScript programming training courses are available at O’Reilly School of Technology for all skill levels.  JavaScript is an open source client-side programming language commonly used as part of a web browser in order to create enhanced user interfaces and dynamic websites.  With classes from OST, you can learn the basics of JavaScript programming and how to use it to suit your professional and creative goals.  OST also offers more advanced classes for further developing your JavaScript skills by incorporating JSON and AJAX. For a full description of the courses or the certificate programs that include one or more of them, explore the links below. If you have any questions or would like additional guidance, don’t hesitate to contact us—we’re here to help!

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