Basic Calculator Using Html And Css

MUAZHAN

6 min read

·

Jul 03, 2024

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Basic Calculator using HTML, CSS, and JavaScript

This article will guide you through building a simple calculator using HTML, CSS, and JavaScript. This project is a great way to learn the fundamentals of web development, including how to structure content with HTML, style it with CSS, and add interactivity with JavaScript.

HTML Structure (index.html)

    
    


    

        

        

            +
            -
            *
            /
            7
            8
            9
            =
            4
            5
            6
            C
            1
            2
            3
            0
            .
        
    

    

• Structure: The HTML creates a calculator div containing the display area and a buttons div for the calculator's interface.
• Buttons: Each button is defined within the buttons div.
• onclick: The onclick attribute triggers JavaScript functions for each button.

CSS Styling (style.css)

body {
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f0f0f0;
}

.calculator {
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

.display {
    background-color: #eee;
    padding: 10px;
    font-size: 24px;
    text-align: right;
    margin-bottom: 10px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 10px;
}

.button {
    background-color: #eee;
    border: none;
    padding: 15px;
    font-size: 18px;
    cursor: pointer;
    border-radius: 5px;
}

.number {
    background-color: #ddd;
}

.operator {
    background-color: #fafafa;
}

.clear {
    background-color: #f08080;
}

• Styling: The CSS provides basic styling to the calculator, display, buttons, and button types.

JavaScript Functionality (script.js)

let display = document.querySelector('.display');
let previousOperator = null;
let previousOperand = null;

function appendNumber(num) {
    display.textContent += num;
}

function appendOperator(operator) {
    previousOperand = parseFloat(display.textContent);
    previousOperator = operator;
    display.textContent += operator;
}

function calculate() {
    let currentOperand = parseFloat(display.textContent.split(previousOperator)[1]);
    let result;

    switch (previousOperator) {
        case '+':
            result = previousOperand + currentOperand;
            break;
        case '-':
            result = previousOperand - currentOperand;
            break;
        case '*':
            result = previousOperand * currentOperand;
            break;
        case '/':
            result = previousOperand / currentOperand;
            break;
    }

    display.textContent = result;
}

function clearDisplay() {
    display.textContent = '';
}

• Variables: Variables are declared to store the display element, previous operator, and previous operand.
• Functions:
  • appendNumber: Appends a number to the display.
  • appendOperator: Appends an operator, stores the previous operand and operator.
  • calculate: Performs the calculation based on the stored operator and operands.
  • clearDisplay: Clears the display.

Running the Calculator

1. Create three files: index.html, style.css, and script.js.
2. Paste the respective code into each file.
3. Open index.html in your web browser.

Now you have a basic calculator! You can enter numbers, operators, and calculate results. You can further enhance this calculator by adding features like:

• Memory: Store previous calculations for easy recall.
• Square root, exponent, etc.: Add more mathematical operations.
• Error Handling: Handle cases like division by zero.
• Visual Improvements: Improve the calculator's appearance and user interface (UI).

This project is a starting point for learning about web development. Feel free to experiment with more complex features and UI designs.