Quick Introduction to React and a Digital clock:

REACT

React is a JavaScript library created by Facebook

React is a User Interface (UI) library

React is a tool for building UI components

DIGITAL CLOCK

A digital clock is a type of clock that displays the time digitally (i.e. in numerals or other symbols), as opposed to an analog clock, where the time is indicated by the positions of rotating hands.

Now we are going to start by creating a react app, Go to any directory of your choice on your window terminal and type the following at the command prompt.

npx create-react-app ticking-clock-with-react

After a successful installation then Change the Directory

cd ticking-clock-with-react

Start the React Application

npm start

You should see this on your browser. Don't worry it might take a couple of minutes.

Happy Hacking!

Now let's open our application in any IDE of your choice, I use visual studio code for my development feel free to use any IDE of your choice. You should see the file structure looking this way:

In the App.js We need to change it from a functional component to a class-based component. You should have something like the screenshot below, if you don't just skip this step.

import React, { Component } from 'react';
import './App.css';

class App extends Component {
render() {
return (
<div className="App">
<div className="clock">
</div>
</div>
);}
}

export default App;

Then your App.css, You should have something like the screenshot below

.App {
text-align: center;
}
.clock {
background-color: #282c34;
min-height: 100vh;
align-items: center;
justify-content: center;
}

Now let us create the clock component with the names clock.js and clock.css for styling it inside the src folder.

Insert the code snippet below into the clock.js component that was created earlier.

import React, { Component } from 'react';
class Clock extends Component {
constructor(props){
super(props);
//This declared the state of time at the very beginning
this.state ={
time: new Date().toLocaleTimeString()
}
}

//This happens when the component mount and the setInterval function get called with a call back function updateClock()
componentDidMount() {
this.intervalID = setInterval(() =>
this.updateClock(),
1000
);}

//This section clears setInterval by calling intervalID so as to optimise memory
componentWillUnmount(){
clearInterval(this.intervalID)
}

//This function set the state of the time to a new time
updateClock(){
this.setState({
time: new Date().toLocaleTimeString()
});
}
render() {
return (
<div className="Time">
     <p> {this.state.time}</p>
</div>
);}
}
export default Clock;

Now you need to import Clock from ‘./clock’; in the App.js file for you to see the clock on your web browser. See Screenshot Below

In the clock.css file add this snippet:

.Time {
height: 500px;
width: 800px;
margin: auto;
position: absolute;
top: 0; left: 0; bottom: 0; right: 0;
padding-top: 70px;
font-family: courier, monospace;
color: white;
font-size: 110px;
}

Now you need to import ‘./clock.css’; in the clock.js as shown below:

On your browser, you should see this

Your App.js should have this:

import React, { Component } from 'react';
import Clock from './clock';
import './App.css';
class App extends Component {
render() {
return (
<div className="App">
<div className="clock">
<Clock />
</div>
</div>
);
}
}
export default App;

Finally: Our clock ticks and works perfectly :)

Click here to find the repository on Github.

Don't forget to star the repo and give a thumbs up here!!!

Thank You!