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Merged
Hrishikesh-Dalal merged 1 commit into from
Oct 27, 2025
Merged

feat: add calculator UI, operations, and keyboard support #188

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52 changes: 41 additions & 11 deletions projects/calculator/index.html
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Original file line number Diff line number Diff line change
@@ -1,18 +1,48 @@
<!doctype html>
<html lang="en">

<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Calculator | Vanilla Verse</title>
<link rel="stylesheet" href="styles.css" />
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Calculator</title>
<link rel="stylesheet" href="styles.css">
</head>

<body>
<header><h1>Calculator</h1></header>
<main id="app">
<!-- TODO: Implement basic calculator UI (display + buttons 0-9, ., +, -, ×, ÷, =, C, ±, %) -->
<!-- TODO: Wire up interactions and keyboard support -->
<!-- TODO: Handle edge cases (divide by zero, multiple decimals, operator chaining) -->
</main>
<script defer src="main.js"></script>
<div class="calculator">
<div class="display">
<div class="previous-operand" id="previousOperand"></div>
<div class="current-operand" id="currentOperand">0</div>
</div>

<div class="buttons">
<button class="function" aria-label="All Clear" data-action="clear">AC</button>
<button class="function" aria-label="Backspace" data-action="backspace">⌫</button>
<button class="function" aria-label="Toggle Sign" data-action="toggle-sign">+/-</button>
<button class="operator" aria-label="Divide" data-action="operator" data-operator="÷">÷</button>

<button aria-label="7" data-number="7">7</button>
<button aria-label="8" data-number="8">8</button>
<button aria-label="9" data-number="9">9</button>
<button class="operator" aria-label="Multiply" data-action="operator" data-operator="×">×</button>

<button aria-label="4" data-number="4">4</button>
<button aria-label="5" data-number="5">5</button>
<button aria-label="6" data-number="6">6</button>
<button class="operator" aria-label="Subtract" data-action="operator" data-operator="−">−</button>

<button aria-label="1" data-number="1">1</button>
<button aria-label="2" data-number="2">2</button>
<button aria-label="3" data-number="3">3</button>
<button class="operator" aria-label="Add" data-action="operator" data-operator="+">+</button>

<button class="zero" aria-label="0" data-number="0">0</button>
<button aria-label="Decimal" data-action="decimal">.</button>
<button class="function" aria-label="Percentage" data-action="percentage">%</button>
<button class="equals" aria-label="Equals" data-action="equals">=</button>
</div>
</div>
<script src="main.js"></script>
</body>

</html>
239 changes: 224 additions & 15 deletions projects/calculator/main.js
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Original file line number Diff line number Diff line change
@@ -1,15 +1,224 @@
/**
* TODO: Calculator logic
* - Render/display current input and result
* - Support operations: +, -, *, /, %, ±, decimal
* - Keyboard support (numbers, operators, Enter for =, Backspace)
* - Prevent invalid inputs (multiple decimals, divide by zero)
* Optional:
* - Expression history
* - Theme toggle
*/

document.addEventListener('DOMContentLoaded', () => {
console.log('Calculator app ready');
// TODO: Build UI or select existing DOM nodes and attach event listeners
});

const currentOperandElement = document.getElementById('currentOperand');
const previousOperandElement = document.getElementById('previousOperand');
const buttons = document.querySelectorAll('button');

let currentOperand = '0';
let previousOperand = '';
let operation = null;
let shouldResetScreen = false;

function init() {
buttons.forEach(button => {
button.addEventListener('click', () => {
button.classList.add('press-animation');
setTimeout(() => button.classList.remove('press-animation'), 200);

handleButtonClick(button);
});
});

document.addEventListener('keydown', handleKeyboardInput);

updateDisplay();
}

function handleButtonClick(button) {
if (button.dataset.number !== undefined) {
appendNumber(button.dataset.number);
} else if (button.dataset.action === 'operator') {
chooseOperation(button.dataset.operator);
} else if (button.dataset.action === 'decimal') {
appendDecimal();
} else if (button.dataset.action === 'equals') {
compute();
} else if (button.dataset.action === 'clear') {
clear();
} else if (button.dataset.action === 'backspace') {
backspace();
} else if (button.dataset.action === 'toggle-sign') {
toggleSign();
} else if (button.dataset.action === 'percentage') {
percentage();
}
}

function handleKeyboardInput(e) {
if (e.key === 'Enter' || e.key === 'Escape' || e.key === 'Backspace') {
e.preventDefault();
}

if (e.key >= '0' && e.key <= '9') {
appendNumber(e.key);
}
else if (e.key === '.') {
appendDecimal();
}
else if (e.key === '+' || e.key === '-' || e.key === '*' || e.key === '/') {
const operatorMap = {
'+': '+',
'-': '−',
'*': '×',
'/': '÷'
};
chooseOperation(operatorMap[e.key]);
}
else if (e.key === 'Enter' || e.key === '=') {
compute();
}
else if (e.key === 'Escape') {
clear();
}
else if (e.key === 'Backspace') {
backspace();
}
}

function appendNumber(number) {
if (shouldResetScreen) {
currentOperand = '';
shouldResetScreen = false;
}

if (currentOperand === '0') {
currentOperand = number;
} else if (currentOperand.length < 12) {
currentOperand += number;
}

updateDisplay();
}

function appendDecimal() {
if (shouldResetScreen) {
currentOperand = '0';
shouldResetScreen = false;
}

if (!currentOperand.includes('.')) {
currentOperand += '.';
}

updateDisplay();
}

function chooseOperation(op) {
if (currentOperand === '') return;

if (previousOperand !== '') {
compute();
}

operation = op;
previousOperand = currentOperand;
shouldResetScreen = true;
updateDisplay();
}

function compute() {
if (operation === null || previousOperand === '') return;

let computation;
const prev = parseFloat(previousOperand);
const current = parseFloat(currentOperand);

if (isNaN(prev) || isNaN(current)) {
clear();
return;
}

switch (operation) {
case '+': computation = prev + current; break;
case '−': computation = prev - current; break;
case '×': computation = prev * current; break;
case '÷':
if (current === 0) {
currentOperand = 'Error';
previousOperand = '';
operation = null;
shouldResetScreen = true;
updateDisplay();
return;
}
computation = prev / current;
break;
default: return;
}

currentOperand = roundResult(computation);
operation = null;
previousOperand = '';
shouldResetScreen = true;
updateDisplay();
}

function clear() {
currentOperand = '0';
previousOperand = '';
operation = null;
shouldResetScreen = false;
updateDisplay();
}

function backspace() {
if (currentOperand.length > 1) {
currentOperand = currentOperand.slice(0, -1);
} else {
currentOperand = '0';
}
updateDisplay();
}

function toggleSign() {
if (currentOperand !== '0') {
currentOperand = currentOperand.startsWith('-')
? currentOperand.slice(1)
: '-' + currentOperand;
}
updateDisplay();
}

function percentage() {
currentOperand = (parseFloat(currentOperand) / 100).toString();
shouldResetScreen = true;
updateDisplay();
}

function roundResult(number) {
const strNumber = number.toExponential(12);
const roundedNumber = parseFloat(strNumber);

return Number.isInteger(roundedNumber)
? roundedNumber.toString()
: roundedNumber.toString();
}

function formatNumber(number) {
if (number === 'Error') return number;

const stringNumber = number.toString();

if (stringNumber.length > 12) {
return parseFloat(number).toExponential(6);
}

return stringNumber;
}

function updateDisplay() {
currentOperandElement.textContent = formatNumber(currentOperand);

if (operation != null) {
previousOperandElement.textContent = `${previousOperand} ${operation}`;
} else {
previousOperandElement.textContent = '';
}

if (currentOperand === 'Error') {
currentOperandElement.classList.add('error');
} else {
currentOperandElement.classList.remove('error');
}
}

init();
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