To create a simple calculator using HTML, CSS, and JavaScript that performs addition, subtraction, multiplication, and division of two numbers.
Step 1: Create an HTML file with:
Step 2: Two input fields for numbers.
Step 3: A dropdown menu for operation selection.
Step 4: A button to perform the calculation.
Step 5: A result display area.
Step 6: Write a CSS file to style the calculator with background, layout, colors, and button hover effects.
Step 7: Write a JavaScript file (script.js) that:
Step 8: Reads the input numbers.
Step 9: Gets the selected operation.
Step 10: Performs the calculation using switch-case.
Step 11: Handles invalid input and division by zero.
Step 12:Displays the result on the webpage.
Step 13: Link HTML, CSS, and JavaScript together and run the project in a web browser.
.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Simple Calculator</title>
<link rel="stylesheet" href="activityStyle.css">
</head>
<body>
<div class="calculator">
<h2>Simple Calculator</h2>
<input type="number" id="num1" placeholder="Enter first number">
<input type="number" id="num2" placeholder="Enter second number">
<select id="operation">
<option value="add">Add</option>
<option value="subtract">Subtract</option>
<option value="multiply">Multiply</option>
<option value="divide">Divide</option>
</select>
<button onclick="calculate()">Calculate</button>
<p id="result"></p>
</div>
<script src="activityScript.js"></script>
</body>
</html>
.css
body {
font-family: Arial, sans-serif;
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
background: linear-gradient(135deg, #89f7fe, #66a6ff);
margin: 0;
}
.calculator {
background: #ffffff;
padding: 25px;
border-radius: 15px;
box-shadow: 0 6px 12px rgba(0,0,0,0.2);
text-align: center;
width: 320px;
}
h2 {
color: #333;
margin-bottom: 15px;
}
input, select {
margin: 10px 0;
padding: 12px;
width: 90%;
font-size: 16px;
border: 2px solid #66a6ff;
border-radius: 8px;
outline: none;
transition: 0.3s;
}
input:focus, select:focus {
border-color: #ff6a95;
box-shadow: 0 0 8px rgba(255, 106, 149, 0.5);
}
button {
margin-top: 15px;
padding: 12px;
width: 95%;
font-size: 16px;
background: #66a6ff;
border: none;
color: white;
font-weight: bold;
border-radius: 8px;
cursor: pointer;
transition: 0.3s;
}
button:hover {
background: #ff6a95;
transform: scale(1.05);
}
#result {
margin-top: 20px;
font-weight: bold;
font-size: 20px;
color: #444;
}
.script
function calculate() {
let num1 = parseFloat(document.getElementById("num1").value);
let num2 = parseFloat(document.getElementById("num2").value);
let operation = document.getElementById("operation").value;
let result = "";
if (isNaN(num1) || isNaN(num2)) {
result = "Please enter valid numbers!";
} else {
switch (operation) {
case "add":
result = num1 + num2;
break;
case "subtract":
result = num1 - num2;
break;
case "multiply":
result = num1 * num2;
break;
case "divide":
result = num2 !== 0 ? num1 / num2 : "Cannot divide by zero!";
break;
}
}
document.getElementById("result").innerText = "Result: " + result;
}
A simple calculator was successfully developed using HTML, CSS, and JavaScript.