props

【props】

　　elements can also represent user-defined components:

　　

　　When React sees an element representing a user-defined component, it passes JSX attributes to this component as a single object. We call this object "props".

　　For example, this code renders "Hello, Sara" on the page:

　　

　　Class components should always call the base constructor with props.

　　

参考：https://facebook.github.io/react/docs/components-and-props.html#rendering-a-component