创建一个新的事件（Event），随之必须调用自身的 init 方法进行初始化。
document.createEvent(type) typeThis method returns a new DOM Event object of the specified type, which must be initialized before use.
此方法返回一个新的特定类型的 DOM Event 对象，此对象在使用前必须经过初始化（init）。
var newEvent = document.createEvent("UIEvents");
EventAttrByteStringCDATASectionCharacterDataChildNodeCommentCustomEventDOMConfigurationDOMErrorDOMErrorHandlerDOMExceptionDOMImplementationDOMImplementationListDOMImplementationRegistryDOMImplementationSourceDOMLocatorDOMObjectDOMParserDOMPointDOMRectDOMStringDOMTimeStampDOMTokenListDOMUserDataDocumentDocumentFragmentDocumentTypeElementElementTraversalEntityEntityReferenceEventTargetHTMLCollectionMutationObserverNodeNodeFilterNodeIteratorNodeListNonDocumentTypeChildNodeProcessingInstructionPromiseResolverRangeTextTextDecoderTextEncoderTimeRangesTreeWalkerTypeInfoUSVStringUserDataHandlerXMLDocument