JavaScriptEssentialsWhenever JavaScript is discussed in the context of (Web host music)
JavaScriptEssentialsWhenever JavaScript is discussed in the context of the Webbrowser environment, it is sometimes difficult to distinguishbetween JavaScript the scripting language and the objects that youuse the language to control. Even so, it s important to separate thelanguage from the object model just enough to help you make impor- tant design decisions when considering JavaScript-enhanced pages. You may come to appreciate the separation in the future if you useJavaScript for other object models, such as server-side programming. All the basics of the language are identical. Only the objects differ. This chapter elaborates on many of the fundamental subjects aboutthe core JavaScript language raised throughout the tutorial (Part II), particularly as they relate to deploying scripts in a world in whichvisitors to your pages may use a wide variety of browsers. Along theway, you receive additional insights into the language itself. You canfind details about the JavaScript core language syntax in Part IV. JavaScript VersionsThe JavaScript language has its own numbering system, which is com- pletely independent of the version numbers assigned to browsers. Thelanguage s creator, Netscape, historically has had the most influenceon the numbering system. The first version, logically enough, was JavaScript 1.0. This was theversion implemented in Navigator 2 and the first release of InternetExplorer 3. As the language evolved with succeeding browser versions, the JavaScript version number incremented in small steps. InternetExplorer 6 and Mozilla-based browsers support JavaScript 1.5. Each successive generation of JavaScript employs additional languagefeatures. For example, in JavaScript 1.0, arrays were not developedfully, causing scripted arrays to not track the number of items in thearray. JavaScript 1.1 filled that hole by providing a constructor func- tion for generating arrays and an inherent lengthproperty for anygenerated array. 1313CHAPTER …In This ChapterHow to separate thelanguage from thedocument object modelWhere scripts go inyour documentsJavaScript languageversionsLanguage highlights for experiencedprogrammers …