What's HTMLElement in Javascript
原文出自：http://javascript.gakaa.com/default.aspx
Every scriptable element object in modern browsers is, at its core, a descendant of the basic HTMLElement abstract object in the W3C DOM. The HTMLElement, itself, inherits properties and methods from the Node and Element chain in the core DOM module. To this inherited set of features, the HTMLElement adds properties that apply to HTML elements (in contrast to XML elements), including the className, dir, id, lang, and title properties. All individual HTML element objects, such as HTMLBodyElement and HTMLFormElement, inherit their characteristics from the HTMLElement object. That's one reason why the list of shared properties and methods is so long: it includes items inherited from the long chain of Node to Element to HTMLElement.
The terminology of the DOM abstract object names (e.g., HTMLBodyElement) is not essential knowledge to scripting element objects. That is to say, the abstract object names almost never appear in scripts because scripts reference instances of such HTML objects by way of their identifiers or through properties of other objects (such as eventObject.target). The only place you are likely to see these abstract names is during debugging, when you use alert( ) methods or other tools to inspect the object referenced by a variable. Netscape 6 reports such object references as instances of a specific HTML element class (e.g., HTMLParagraphElement or HTMLInputElement). This information, in itself, is often far more helpful than IE's reporting of the reference being just [object].
Every scriptable element object in modern browsers is, at its core, a descendant of the basic HTMLElement abstract object in the W3C DOM. The HTMLElement, itself, inherits properties and methods from the Node and Element chain in the core DOM module. To this inherited set of features, the HTMLElement adds properties that apply to HTML elements (in contrast to XML elements), including the className, dir, id, lang, and title properties. All individual HTML element objects, such as HTMLBodyElement and HTMLFormElement, inherit their characteristics from the HTMLElement object. That's one reason why the list of shared properties and methods is so long: it includes items inherited from the long chain of Node to Element to HTMLElement.
The terminology of the DOM abstract object names (e.g., HTMLBodyElement) is not essential knowledge to scripting element objects. That is to say, the abstract object names almost never appear in scripts because scripts reference instances of such HTML objects by way of their identifiers or through properties of other objects (such as eventObject.target). The only place you are likely to see these abstract names is during debugging, when you use alert( ) methods or other tools to inspect the object referenced by a variable. Netscape 6 reports such object references as instances of a specific HTML element class (e.g., HTMLParagraphElement or HTMLInputElement). This information, in itself, is often far more helpful than IE's reporting of the reference being just [object].
