ReactJS Update parent's state from child component

by ybeaz

HTML

<script src="https://unpkg.com/react@15/dist/react.min.js"></script>
<script src="https://unpkg.com/react-dom@15/dist/react-dom.min.js"></script>
<div id="demo">134</div>

Babel + JSX

//ChildB component
	class ChildB extends React.Component {

		render() {
			
			var	handleToUpdate	=	this.props.handleToUpdate;
			return (<div><button onClick={() => handleToUpdate('someVar')}>Push me</button></div>
			)
		}
	}

	//ParentA component
	class ParentA extends React.Component {	
	    constructor(props) {
			super(props);
		}

		handleToUpdate = (someArg) => {
				alert('We pass argument from Child to Parent: ' + someArg);
		}

		render() {
			return (<div>
				<ChildB handleToUpdate = {this.handleToUpdate} /></div>)
		}
	}

	if(document.querySelector("#demo")){
		ReactDOM.render(
			<ParentA />,
			document.querySelector("#demo")
		);
	}