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How to make Incremental and Decremental

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

  • index.html
    <h1>Increment and Decrement counter</h1>

    <div="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>

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.

  • style.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%;
}

Step 3: Now, we will add some JavaScript code to add functionality to the buttons which we have created earlier. Refer to the comments in the code for help.

  • index.js

//initialising a variable name data

var 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;
}

Complete Code: In this section, we will combine the above three sections to create a counter.

  • HTML
<!DOCTYPE html>
<html>
	<head>
		<!-- CSS code-->

		<style>
			/*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%;
			}
		</style>
	</head>

	<body>
		<!-- give a suitable heading using h1 tag-->
		<h1>Increment and Decrement counter</h1>

		<div ="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>
		<!-- JavaScript code-->
		<script>
			//initialising a variable name data
			var 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;
			}
		</script>
	</body>
</html>

Output:

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