react eventlistener code example

Example 1: event listener for functional component

import React, { useEffect } from 'react';

const Component = (props) => {  
  useEffect(() => {
    window.addEventListener('scroll', handleScroll);
  });
  useEffect(() => {
    return () => {
      window.removeEventListener('scroll', handleScroll);
    };
  }, []);

  function handleScroll() {
    let scrollTop = window.scrollY;
  }


  return ()
}

Example 2: event listener in react

var Box = React.createClass({
  getInitialState: function() {
    return {windowWidth: window.innerWidth};
  },

  handleResize: function(e) {
    this.setState({windowWidth: window.innerWidth});
  },

  componentDidMount: function() {
    window.addEventListener('resize', this.handleResize);
  },

  componentWillUnmount: function() {
    window.removeEventListener('resize', this.handleResize);
  },

  render: function() {
    return <div>Current window width: {this.state.windowWidth}</div>;
  }
});

ReactDOM.render(<Box />, mountNode);

Example 3: react event listener

// it a component
import React from 'react';

class App extends React.Component {
      //call function (ECMAScript 5) from tag input:text
  handleChange = e => {
    //
    console.log(`${e.target.value}`)
  }
  render() { 
    return (
      <div className="App">
        <input type="text" name="input" id="" placeholder="" onChange={this.handleChange}/>
      </div>
    );
}
}

export default App;

Example 4: react event listener

onClick onContextMenu onDoubleClick onDrag onDragEnd onDragEnter onDragExit
onDragLeave onDragOver onDragStart onDrop onMouseDown onMouseEnter onMouseLeave
onMouseMove onMouseOut onMouseOver onMouseUp