How to make Incremental and Decremental counter using HTML, CSS and JavaScript ?

Last Updated : 22 Dec, 2023

While visiting different shopping websites like Flipkart and Amazon you have seen a counter on each product, that counter is used to specify the quantity of that product. Hence, the counter is a very useful part of many websites. In this article, we will design a counter using HTML, CSS, and JavaScript.

Output Preview:

Screenshot-2023-12-21-202052

Approach:

First, we will design a simple button using HTML. Refer to the comments in the code.
Next, we will use some CSS properties to design the button and use the hover class to get the animation effect when we hover the mouse over the button.
Now, we will add some JavaScript code to add functionality to the buttons which we created earlier. Refer to the comments in the code for help.

Example: In this example, we are following above explained approach.

Javascript

//initialising a variable name data
 
let data = 0;
 
//printing default value of data that is 0 in h2 tag
document.getElementById("counting").innerText = data;
 
//creation of increment function
function increment() {
    data = data + 1;
    document.getElementById("counting").innerText = data;
}
//creation of decrement function
function decrement() {
    data = data - 1;
    document.getElementById("counting").innerText = data;
}

HTML

<!DOCTYPE HTML>
 
<html>
 
<head>
    <meta http-equiv="Content-Type"
        content="text/html; charset=UTF-8" />
     
</head>
     
<body>
<!-- give a suitable heading using h1 tag-->
        <h1>Increment and Decrement counter</h1>
 
        <div class="container">            
        <!-- adding button and heading to show the digits -->
        <!--increment() and decrement() functions on button click-->
            <button onclick="increment()">+</button>
            <h2 id="counting"></h2>
            <button onclick="decrement()">-</button>        
        </div>
 
</body>
 
</html>

CSS

/*apply css properties to body tag*/
 
body {
    position: absolute;
    left: 0%;
    text-align: center;
}
 
/*apply css properties to container class*/
 
.container {
    justify-content: center;
    align-items: center;
    display: flex;
    height: 100%;
    text-align: center;
}
 
/*apply css properties to button tag*/
 
button {
    width: 90px;
    height: 60px;
    font-size: 30px;
    background-color: green;
    color: honeydew;
}
 
/*apply hover effect to button tag*/
 
button:hover {
    background-color: greenyellow;
    color: grey;
}
 
/*apply css properties to h2 tag*/
 
h2 {
    color: black;
    margin: 0 50px;
    font-size: 45px;
}
 
/*apply css properties to h1 tag*/
 
h1 {
    font-size: 35px;
    color: green;
    text-align: center;
    padding-left: 10%;
}