added clock

src/App.js

@@ -1,25 +1,30 @@
-import logo from './logo.svg';
-import './App.css';
+import "./App.css";
+import React, { Component } from "react";
 
-function App() {
-  return (
-    <div className="App">
-      <header className="App-header">
-        <img src={logo} className="App-logo" alt="logo" />
-        <p>
-          Edit <code>src/App.js</code> and save to reload.
-        </p>
-        <a
-          className="App-link"
-          href="https://reactjs.org"
-          target="_blank"
-          rel="noopener noreferrer"
-        >
-          Learn React
-        </a>
-      </header>
-    </div>
-  );
+class App extends Component {
+  constructor() {
+    super();
+    this.state = {
+      time: new Date(),
+    };
+  }
+
+  currentTime() {
+    this.setState({
+      time: new Date(),
+    });
+  }
+  componentDidMount() {
+    setInterval(() => this.currentTime(), 1000);
+  }
+
+  render() {
+    return (
+      <div className="App">
+        <h1>{this.state.time.toLocaleTimeString()}</h1>
+      </div>
+    );
+  }
 }
 
 export default App;