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JavaScript for Web Developers

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2 ��� CHAPTER 1 WHAT IS JAVASCRIPT? A SHORT HISTORY As the Web gained popularity, a gradual demand for client-side scripting languages developed. At the time, most Internet users were connecting over a 28.8 kbps modem even though web pages were growing in size and complexity. Adding to users��� pain was the large number of round-trips to the server required for simple form validation. Imagine ��� lling out a form, clicking the Submit button, waiting 30 seconds for processing, and then being met with a message indicating that you forgot to complete a required ���eld. Netscape, at that time on the cutting edge of technological innovation, began seriously considering the development of a client-side scripting language to handle simple processing. Brendan Eich, who worked for Netscape at the time, began developing a scripting language called Mocha, and later LiveScript, for the release of Netscape Navigator 2 in 1995, with the intention of using it both in the browser and on the server (where it was to be called LiveWire). Netscape entered into a development alliance with Sun Microsystems to complete the implementation of LiveScript in time for release. Just before Netscape Navigator 2 was of���cially released, Netscape changed LiveScript���s name to JavaScript to capitalize on the buzz that Java was receiving from the press. Because JavaScript 1.0 was such a hit, Netscape released version 1.1 in Netscape Navigator 3. The popularity of the ���edgling Web was reaching new heights, and Netscape had positioned itself to be the leading company in the market. At this time, Microsoft decided to put more resources into a competing browser named Internet Explorer. Shortly after Netscape Navigator 3 was released, Microsoft introduced Internet Explorer 3 with a JavaScript implementation called JScript (so called to avoid any possible licensing issues with Netscape). This major step for Microsoft into the realm of web browsers in August 1996 is now a date that lives in infamy for Netscape, but it also represented a major step forward in the development of JavaScript as a language. Microsoft���s implementation of JavaScript meant that there were two different JavaScript versions ���oating around: JavaScript in Netscape Navigator and JScript in Internet Explorer. Unlike C and many other programming languages, JavaScript had no standards governing its syntax or features, and the three different versions only highlighted this problem. With industry fears mounting, it was decided that the language must be standardized. In 1997, JavaScript 1.1 was submitted to the European Computer Manufacturers Association (Ecma) as a proposal. Technical Committee #39 (TC39) was assigned to ���standardize the syntax and semantics of a general purpose, cross-platform, vendor-neutral scripting language��� (www.ecma-international.org/memento/TC39.htm). Made up of programmers from Netscape, Sun, Microsoft, Borland, NOMBAS, and other companies with interest in the future of scripting, TC39 met for months to hammer out ECMA-262, a standard de��� ning a new scripting language named ECMAScript (often pronounced as ���ek-ma-script���). The following year, the International Organization for Standardization and International Electrotechnical Commission (ISO/IEC) also adopted ECMAScript as a standard (ISO/IEC-16262). Since that time, browsers have tried, with varying degrees of success, to use ECMAScript as a basis for their JavaScript implementations. www.it-ebooks.info c01.indd 2 12/8/11 9:23:16 AM

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