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A common pattern used to share state between components is to use the children prop.
Inside a component JSX you can render {this.props.children} which automatically injects any JSX passed in the parent component as a children:
class Parent extends React.Component {
constructor(props) {
super(props)
this.state = {
/*...*/
}
}
render() {
return <div>{this.props.children}</div>
}
}
const Children1 = () => {}
const Children2 = () => {}
const App = () => (
<Parent>
<Children1 />
<Children2 />
</Parent>
)
However, there is a problem here: the state of the parent component cannot be accessed from the children.
To be able to share the state, you need to use a render prop component, and instead of passing components as children of the parent component, you pass a function which you then execute in {this.props.children()}. The function can accept arguments, :
class Parent extends React.Component {
constructor(props) {
super(props)
this.state = { name: 'Flavio' }
}
render() {
return <div>{this.props.children(this.state.name)}</div>
}
}
const Children1 = props => {
return <p>{props.name}</p>
}
const App = () => <Parent>{name => <Children1 name={name} />}</Parent>
Instead of using the children prop, which has a very specific meaning, you can use any prop, and so you can use this pattern multiple times on the same component:
class Parent extends React.Component {
constructor(props) {
super(props)
this.state = { name: 'Flavio', age: 35 }
}
render() {
return (
<div>
<p>Test</p>
{this.props.someprop1(this.state.name)}
{this.props.someprop2(this.state.age)}
</div>
)
}
}
const Children1 = props => {
return <p>{props.name}</p>
}
const Children2 = props => {
return <p>{props.age}</p>
}
const App = () => (
<Parent
someprop1={name => <Children1 name={name} />}
someprop2={age => <Children2 age={age} />}
/>
)
ReactDOM.render(<App />, document.getElementById('app'))