Component vs Element vs Instance
Component
function,继承自ReactBaseComponent
Element
:Object,通过createElement(Component)
创建
Instance
通过instantiateReactComponent
实例化, 属性_currentElement即是Element
markup
Markup refers to the sequence of characters or other symbols that you insert at certain places in a text or word processing file to indicate how the file should look when it is printed or displayed or to describe the document’s logical structure.