<language> (Formerly "LiveScript") Netscape's simple, cross-platform, World-Wide Web scripting language, only very vaguely related to Java (which is a Sun trademark). JavaScript is intimately tied to the World-Wide Web, and currently runs in only three environments - as a server-side scripting language, as an embedded language in server-parsed HTML, and as an embedded language run in web browsers where it is the most important part of DHTML. JavaScript has a simplified C-like syntax and is tightly integrated with the browser Document Object Model. It is useful for implementing enhanced forms, simple web database front-ends, and navigation enhancements. It is unusual in that the scope of variables extends throughout the function in which they are declared rather than the smallest enclosing block as in C. JavaScript originated from Netscape and, for a time, only their products supported it. Microsoft now supports a work-alike which they call JScript. The resulting inconsistencies make it difficult to write JavaScript that behaves the same in all browsers. This could be attributed to the slow progress of JavaScript through the standards bodies. JavaScript runs "100x" slower than C, as it is purely interpreted (Java runs "10x" slower than C code). Netscape and allies say JavaScript is an "open standard" in an effort to keep Microsoft from monopolising web software as they have desktop software. Netscape and Sun have co-operated to enable Java and JavaScript to exchange messages and data. See also VBScript. Usenet newsgroup: news:comp.lang.javascript. Mailing List: <majordomo@obscure.org> ("subscribe javascript" in body). (2003-04-28)

A JavaScript engine is a software component that executes JavaScript code. The first JavaScript engines were mere interpreters, but all relevant modern engines use just-in-time compilation for improved performance.