尝试使用JS构建计算器

<div id="calculator">
  <input type="text" id="display" readonly>
  <button onclick="appendNumber(7)">7</button>
  <button onclick="appendNumber(8)">8</button>
  <button onclick="appendNumber(9)">9</button>
  <button onclick="appendOperator('+')">+</button>
  <button onclick="appendNumber(4)">4</button>
  <button onclick="appendNumber(5)">5</button>
  <button onclick="appendNumber(6)">6</button>
  <button onclick="appendOperator('-')">-</button>
  <button onclick="appendNumber(1)">1</button>
  <button onclick="appendNumber(2)">2</button>
  <button onclick="appendNumber(3)">3</button>
  <button onclick="appendOperator('*')">*</button>
  <button onclick="appendNumber(0)">0</button>
  <button onclick="calculate()">=</button>
  <button onclick="appendOperator('/')">/</button>
  <button onclick="clearDisplay()">C</button>
</div>

#calculator {
  width: 200px;
  border: 1px solid #ccc;
  padding: 10px;
}

#display {
  width: 100%;
  margin-bottom: 10px;
}

button {
  width: 40px;
  height: 40px;
  margin: 5px;
}

let display = document.getElementById('display');
let expression = '';

function appendNumber(number) {
  expression += number;
  display.value = expression;
}

function appendOperator(operator) {
  expression += operator;
  display.value = expression;
}

function calculate() {
  try {
    let result = eval(expression);
    display.value = result;
    expression = '';
  } catch (error) {
    display.value = 'Error';
  }
}

function clearDisplay() {
  expression = '';
  display.value = '';
}