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

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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.

A sample image is provided to give you a more clear idea about the article.

Step-by-step implementation:

Step 1: First, we will design a simple button using HTML. Refer to the comments in the code.

Step 2: 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.

Step 3: 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:

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%;
}

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;
}