beginners-guide-to-react-base/13-side-effects.html at main · volta2016/beginners-guide-to-react-base · GitHub

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>
      Manage side-effects in a React Component with the useEffect hook
    </title>
  </head>
  <style>
    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
        Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    }
  </style>
  <body>
    <div id="root"></div>

    <script
      src="https://unpkg.com/react@17/umd/react.production.min.js"
      crossorigin
    ></script>
    <script
      src="https://unpkg.com/react-dom@17/umd/react-dom.production.min.js"
      crossorigin
    ></script>
    <script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
    <script type="text/babel">
      const state = { eventCount: 0, username: "" };

      function Greetings() {
        const [name, setName] = React.useState(
          window.localStorage.getItem("name" || "")
        ); //obtiene

        React.useEffect(() => {
          window.localStorage.setItem("name", name); //guarda actualiza
        });

        const handleChange = (event) => setName(event.target.value);

        return (
          <div>
            <form>
              <label htmlFor="name">name:</label>
              <input
                value={name}
                onChange={handleChange}
                id="name"
                type="text"
              />
            </form>
            {name ? (
              <strong>Hello {name}</strong>
            ) : (
              <p>Please type your name</p>
            )}
          </div>
        );
      }

      ReactDOM.render(<Greetings />, document.getElementById("root"));
    </script>
  </body>
</html>