Creating interactive applications is both challenging and rewarding. One classic example is a calculator app, which not only serves as a practical tool but also offers a great opportunity to learn fundamental JavaScript concepts.
In this article, we'll embark on a journey to build a simple calculator application using JavaScript.
For simplicity, I'll create a calculator with basic arithmetic operations (addition, subtraction, multiplication, division).
Understanding the Basic:
Before diving into the code, let's outline the basic functionalities our calculator app should have:
Display: A display area to show the input and output of calculations.
Buttons: Buttons representing numbers, arithmetic operators, and other controls like "Clear" and "Equals".
Arithmetic Operations: Support for basic arithmetic operations like addition, subtraction, multiplication, and division.
Setting Up the HTML Structure
We'll start by creating the structure of our calculator using HTML.
Here's a basic template to get us started:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Build Calculator App</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="calculator">
<input type="text" id="result" readonly>
<div class="keys">
<button onclick="appendNumber('7')">7</button>
<button onclick="appendNumber('8')">8</button>
<button onclick="appendNumber('9')">9</button>
<button class="minus" onclick="appendOperator('+')">+</button>
<button onclick="appendNumber('4')">4</button>
<button onclick="appendNumber('5')">5</button>
<button onclick="appendNumber('6')">6</button>
<button class="minus" onclick="appendOperator('-')">-</button>
<button onclick="appendNumber('1')">1</button>
<button onclick="appendNumber('2')">2</button>
<button onclick="appendNumber('3')">3</button>
<button class="minus" onclick="appendOperator('*')">*</button>
<button onclick="appendNumber('0')">0</button>
<button class="minus" onclick="clearResult()">C</button>
<button class="minus" onclick="calculateResult()">=</button>
<button class="minus" onclick="appendOperator('/')">/</button>
</div>
</div>
<script src="script.js"></script>
</body>
</html>
Styling the Calculator
While styling isn't the primary focus of this tutorial, we'll add some basic CSS to make our calculator visually appealing and user-friendly.
Feel free to customize the styles according to your preference.
CSS Structure:
@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@500&display=swap');
* {
font-family: 'Poppins', sans-serif;
}
body {
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
background-color: #c2b2d8;
}
.calculator {
background-color: #090012;
border-radius: 10px;
padding: 20px;
box-shadow: 0 0 10px rgba(0, 0, 0, .2);
}
#result {
width: calc(100% - 20px);
margin-bottom: 10px;
padding: 10px;
font-size: 20px;
border-radius: 10px;
border: none;
outline: none;
}
.keys {
display: grid;
grid-template-columns: repeat(4, 1fr);
grid-gap: 10px;
}
button {
padding: 10px;
font-size: 18px;
background-color: #ffffff;
color: #000000;
border: none;
border-radius: 5px;
cursor: pointer;
font-weight: 600;
outline: none;
}
button:hover {
background-color: #e9d8f7;
}
.minus{
background-color: rgb(245, 113, 197);
font-weight: 500;
color: white;
}
.minus:hover{
background-color: rgb(243, 81, 184);
}
Implementing JavaScript Functionality:
Now, let's add the JavaScript logic to make our calculator functional. We'll define functions to handle number input, arithmetic operations, and calculation.
let result = document.getElementById('result');
function appendNumber(num) {
result.value += num;
}
function appendOperator(operator) {
result.value += operator;
}
function clearResult() {
result.value = '';
}
function calculateResult() {
try {
result.value = eval(result.value);
} catch (error) {
result.value = 'Error';
}
}
Wrapping Up
Congratulations! You've built a basic calculator app using JavaScript. While this example covers only the essentials, there's a lot more you can do to enhance its functionality and appearance.
Consider adding support for decimal numbers, handling keyboard input, or implementing more advanced operations.
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