Skip to content
Snippets Groups Projects
Select Git revision
  • master default protected
1 result
Blame Permalink
Code owners
Assign users and groups as approvers for specific file changes. Learn more.
lifecycle.html 3.15 KiB 
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8" />
<title>Lifecycle Methods</title>
<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

<style>
    #container {
      padding: 50px;
      background-color: #FFF;
    }
  </style>
</head>
<body>
  <div id="container"></div>
  
  <script type="text/babel">
    var destination = document.querySelector("#container");

    class Counter extends React.Component {
      render() {
        var textStyle = {
          fontSize: 72,
          fontFamily: "sans-serif",
          color: "#333",
          fontWeight: "bold"
        };

        console.log("render: Counter component");
      
        return (
          <div style={textStyle}>
            {this.props.display}
          </div>
        );
      }
    }

    class CounterParent extends React.Component {
      constructor(props) {
        super(props);
        console.log("constructor: It's default time!");

        this.state = {
          count: 0
        };
        this.increase = this.increase.bind(this);
      }

      increase() {
        this.setState({
          count: this.state.count + 1
        });
      }

      static getDerivedStateFromProps(props, state) {
        console.log("getDerivedStateFromProps: You probably don't need this!")

        return null;
      }

      componentDidUpdate(currentProps, currentState) {
        console.log("componentDidUpdate: Component just updated!");
      }

      getSnapshotBeforeUpdate(prevProps, prevState) {
        console.log("getSnapshotBeforeUpdate: Component is about to commit its changes!")

        return null;
      }

      componentDidMount() {
        console.log("componentDidMount: Component is inserted into the tree!");
      }

      componentWillUnmount() {
        console.log("componentWillUnmount: Component is about to be removed from the DOM!");
      }

      shouldComponentUpdate(newProps, newState) {
        console.log("shouldComponentUpdate: Should component update?");
        console.log(newProps)
        console.log(newState)
        console.log(destination)
        if (newState.count < 5) {
          console.log("shouldComponentUpdate: Component should update!");
          return true;
        } else {
          ReactDOM.unmountComponentAtNode(destination);
          console.log("shouldComponentUpdate: Component should not update!");
          return false;
        }
      }

      render() {
        var backgroundStyle = {
          padding: 50,
          border: "#333 2px dotted",
          width: 250,
          height: 100,
          borderRadius: 10,
          textAlign: "center"
        };
        console.log("render: CounterParent component");
        return (
          <div style={backgroundStyle}>
            <Counter display={this.state.count} />
            <button onClick={this.increase}>
              +
            </button>
          </div>
        );
      }
    };

    ReactDOM.render(
      <div>
        <CounterParent />
      </div>,
      destination
    );
  </script>
</body>

</html>