React communication component (Sons pass component value)

1, traditional values ​​parent component subassembly

When referring to sub-assembly is transmitted, the equivalent of a property, for example: in the value of this sub-assembly obtained by param porps.param.

Parent component subassembly to the traditional values, by propsthe parent element stateis transmitted to the subassembly.

Parent component code snippet:

constructor(props){
    super(props)
    this.state={
      message: