<script>
function appendNumber(number) {
document.getElementById('display').value += number;
}
function appendOperator(operator) {
document.getElementById('display').value += ' ' + operator + ' ';
}
function clearDisplay() {
document.getElementById('display').value = '';
}
function calculate() {
try {
let display = document.getElementById('display').value;
document.getElementById('display').value = eval(display);
} catch (e) {
document.getElementById('display').value = 'Error';
}
}
document.addEventListener('keydown', function(event) {
const key = event.key;
if (key >= '0' && key <= '9') {
appendNumber(key);
} else if (key === '+' || key === '-' || key === '*' || key === '/') {
appendOperator(key);
} else if (key === 'Enter') {
calculate();
} else if (key === 'Escape') {
clearDisplay();
} else if (key === '.') {
appendNumber('.');
}
});
</script>