pass value up from component react code example

Example 1: pass element from child to parent react

Parent:

<div className="col-sm-9">
     <SelectLanguage onSelectLanguage={this.handleLanguage} /> 
</div>

Child:

handleLangChange = () => {
    var lang = this.dropdown.value;
    this.props.onSelectLanguage(lang);            
}

Example 2: react pass parameter to component

import React, { Component } from 'react'; class App extends Component {  render() {    return (      <div>        <Greeting />      </div>    );  }} class Greeting extends Component {  render() {    const greeting = 'Welcome to React';     return <h1>{greeting}</h1>;  }} export default App;