HTMLDocument is an abstract interface of the DOM which provides access to special properties and methods not present by default on a regular (XML) document.
Its methods and properties are included in the document page and listed separately in their own section in the above linked DOM page.
HTMLDocument 对象继承了document接口和HTMLDocument接口。因此它有比document更多的属性。并且与XMLDocument不同的是，HTMLDocument是具有外观的，并且要管理它后代的HTMLElement。
HTMLDocumentBeforeUnloadEventDOMStringMapDataTransferDragEventErrorEventGlobalEventHandlersHTMLAnchorElementHTMLAreaElementHTMLAudioElementHTMLBRElementHTMLBaseElementHTMLBaseFontElementHTMLBodyElementHTMLButtonElementHTMLCanvasElementHTMLContentElementHTMLDListElementHTMLDataElementHTMLDataListElementHTMLDialogElementHTMLDivElementHTMLElementHTMLEmbedElementHTMLFieldSetElementHTMLFormControlsCollectionHTMLFormElementHTMLFrameSetElementHTMLHRElementHTMLHeadElementHTMLHeadingElementHTMLHtmlElementHTMLIFrameElementHTMLImageElementHTMLInputElementHTMLIsIndexElementHTMLKeygenElementHTMLLIElementHTMLLabelElementHTMLLegendElementHTMLLinkElementHTMLMapElementHTMLMediaElementHTMLMetaElementHTMLMeterElementHTMLModElementHTMLOListElementHTMLObjectElementHTMLOptGroupElementHTMLOptionElementHTMLOptionsCollectionHTMLOutputElementHTMLParagraphElementHTMLParamElementHTMLPictureElementHTMLPreElementHTMLProgressElementHTMLQuoteElementHTMLScriptElementHTMLSelectElementHTMLShadowElementHTMLSourceElementHTMLSpanElementHTMLStyleElementHTMLTableCaptionElementHTMLTableCellElementHTMLTableColElementHTMLTableDataCellElementHTMLTableElementHTMLTableHeaderCellElementHTMLTableRowElementHTMLTableSectionElementHTMLTextAreaElementHTMLTimeElementHTMLTitleElementHTMLTrackElementHTMLUListElementHTMLUnknownElementHTMLVideoElementHashChangeEventHistoryImageDataLocationMessageChannelMessageEventMessagePortNavigatorNavigatorGeolocationNavigatorIDNavigatorLanguageNavigatorOnLineNavigatorPluginsPageTransitionEventPluginPluginArrayPopStateEventPortCollectionRadioNodeListTransferableValidityStateWebVTTWindowWindowBase64WindowEventHandlersWindowTimers