MkDay

Posted on Dec 6, 2021

Simple LED-Number-Display With CSS Borders And JavaScript

#javascript #beginners #css #productivity

Have you ever wondered how to display numbers on a digital clock or a basic calculator?

Well, you can think about it in this way.

There are seven red lines made up of red LED bulbs. And they are arranged like two rectangles. Also, one of the rectangles appears on top of the other.

Wikipedia refers to this LED-Number-Display as Seven-Segment Display.

However, if you want to create one, you only need to follow these three simple steps. I promise it won't take more than one hour.

Steps to create a LED-Number-Display (Seven-Segment-Display)

Step 1. HTML: Create two rectangles.
Step 2. CSS: Add borders separately for each side of the two rectangles.
Step 3. JavaScript: Display digits by changing the border color on each side of the rectangles.

So let's follow the steps.

1. HTML: Create two rectangles

Create the parent div:

<div id="container">

Create the two child-div inside parent div:

<div id="top-box"> and <div id="bottom-box">

Here is the HTML code:


<body>
  <h1>LED Number Display</h1>
  <div id="container">

    <div id="top-box"></div>
    <div id="bottom-box"></div>

  </div>

</body>

2. CSS: Add borders separately for each side of the two rectangles.

First of all,

Give the same width and height for the both #top-box and #bottom-box.
Place them one on top of the other using CSS flex.

And then,

Create borders separately for each side of both elements.

For the top-box:


 border-left: 10px ridge transparent;
 border-right: 10px ridge transparent;
 border-top: 10px ridge transparent;
 border-bottom: 5px inset transparent;

For the bottom-box:


 border-left: 10px ridge transparent;
 border-right: 10px ridge transparent;
 border-top: 5px inset transparent; 
 border-bottom: 10px ridge transparent;

Here is the CSS code:


html {
  font-size: 62.5%;
  color: Navy;
  text-shadow: 1px 1px 2px #000;
  font-family: sans-serif;
}

@media (max-width: 75em) {
  html {
    font-size: 60%;
  }
}

@media (max-width: 61.25em) {
  html {
    font-size: 58%;
  }
}

@media (max-width: 28.75em) {
  html {
    font-size: 55%;
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-around;
  padding: 3rem;
  background: DarkSeaGreen;
}

#container {
  margin-top: 3rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 500px;
  height: 300px;
  background: #555;
  border: ridge 8px BurlyWood;
  border-radius: 30px;
  box-shadow: 0 0.6rem 0.6rem rgba(0, 0, 0, 0.33);
}

#top-box {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100px;
  height: 100px;
  background: #555;
  border-left: 10px ridge transparent;
  border-right: 10px ridge transparent;
  border-top: 10px ridge transparent;
  border-bottom: 5px inset transparent;
  border-radius: 10px;
}

#bottom-box {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100px;
  height: 100px;
  background: #555;
  border-left: 10px ridge transparent;
  border-right: 10px ridge transparent;
  border-top: 5px inset transparent;
  border-bottom: 10px ridge transparent;
  border-radius: 10px;
}

3. JavaScript: Display digits by changing the colors of each border.

Select elements.


let topBox = document.querySelector('#top-box');
let bottomBox = document.querySelector('#bottom-box');

Create two variables to store colors red and transparent.

Eg: let on='red' and let off='transparent'.

Create ten functions to display each digit from 0 to 9.

Eg: let zero = () => {...} to let nine = () => {...}

Change the border color of both div using the variables on and off to display a specific digit.

Eg:

topBox.style.borderTopColor = on;
bottomBox.style.borderTopColor = off;

If you want, you can animate those digits repeatedly using setTimeout() and setInterval().

Here is the JavaScript code:


let topBox = document.querySelector("#top-box");

let bottomBox = document.querySelector("#bottom-box");

let on = "Snow";
let off = "transparent";

let zero = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = off;

  bottomBox.style.borderTopColor = off;
  bottomBox.style.borderLeftColor = on;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

let one = () => {
  topBox.style.borderTopColor = off;
  topBox.style.borderLeftColor = off;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = off;
  topBox.style.borderBottomColor = off;

  bottomBox.style.borderTopColor = off;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = off;
};

let two = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = off;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = on;
  bottomBox.style.borderRightColor = off;
  bottomBox.style.borderBottomColor = on;
};

let three = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = off;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

let four = () => {
  topBox.style.borderTopColor = off;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = off;
};

let five = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = off;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

let six = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = off;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = on;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

let seven = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = off;

  bottomBox.style.borderTopColor = off;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = off;
};

let eight = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = on;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

let nine = () => {
  topBox.style.borderTopColor = on;
  topBox.style.borderLeftColor = on;
  topBox.style.borderRightColor = on;
  topBox.style.borderBottomColor = on;

  bottomBox.style.borderTopColor = on;
  bottomBox.style.borderLeftColor = off;
  bottomBox.style.borderRightColor = on;
  bottomBox.style.borderBottomColor = on;
};

function playNumbers() {
  setTimeout(zero, 0);
  setTimeout(one, 1000);
  setTimeout(two, 2000);
  setTimeout(three, 3000);
  setTimeout(four, 4000);
  setTimeout(five, 5000);
  setTimeout(six, 6000);
  setTimeout(seven, 7000);
  setTimeout(eight, 8000);
  setTimeout(nine, 9000);
}

playNumbers();
setInterval(playNumbers, 10000);

Now you are done creating your LED Number Display.

Here is the live demo for the LED Number Display.

If you have any ideas to create this differently, feel free to mention them below.

Happy Coding!

Image Credit: Chris barker on Flickr

DEV Community

Simple LED-Number-Display With CSS Borders And JavaScript

Steps to create a LED-Number-Display (Seven-Segment-Display)

1. HTML: Create two rectangles

2. CSS: Add borders separately for each side of the two rectangles.

3. JavaScript: Display digits by changing the colors of each border.

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