<!DOCTYPE html>
<html>
<head>
<title>Calculator</title>
<script>
function addDigit(digit) {
var resultField = document.getElementById("result");
resultField.value += digit;
}
function calculate() {
var calculation = document.getElementById("result").value;
var resultField = document.getElementById("result");
if(calculation) {
try {
resultField.value = eval(calculation);
} catch(error) {
resultField.value = "Error";
}
} else {
resultField.value = "";
}
}
function clearResult() {
var resultField = document.getElementById("result");
resultField.value = "";
}
</script>
</head>
<body>
<h2>Calculator</h2>
<input type="text" id="result" readonly><br><br>
<button onclick="addDigit('1')">1</button>
<button onclick="addDigit('2')">2</button>
<button onclick="addDigit('3')">3</button>
<button onclick="addDigit('+')">+</button><br><br>
<button onclick="addDigit('4')">4</button>
<button onclick="addDigit('5')">5</button>
<button onclick="addDigit('6')">6</button>
<button onclick="addDigit('-')">-</button><br><br>
<button onclick="addDigit('7')">7</button>
<button onclick="addDigit('8')">8</button>
<button onclick="addDigit('9')">9</button>
<button onclick="addDigit('*')">×</button><br><br>
<button onclick="clearResult()">C</button>
<button onclick="addDigit('0')">0</button>
<button onclick="addDigit('.')">.</button>
<button onclick="addDigit('/')">÷</button><br><br>
<button onclick="calculate()">=</button>
</body>
</html>
ジョーク: "Why did the calculator break up with the pencil? Because it couldn't handle its decimal places."
