AI 生成: 一个简洁美观的网页计算器，支持加、减、乘、除和清除功能，使用纯 HTML/CSS/JavaScript 实现。

script.js

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+// ===== 计算器状态 =====
+let currentInput = '0';      // 当前输入的数字字符串
+let previousValue = null;    // 上一个操作数
+let currentOperator = null;  // 当前运算符
+let shouldResetInput = false; // 下次输入是否覆盖当前值
+
+// ===== DOM 元素 =====
+const display = document.getElementById('display');
+
+/**
+ * 更新显示区域
+ */
+function updateDisplay() {
+  display.textContent = currentInput;
+}
+
+/**
+ * 输入数字
+ * @param {string} num
+ */
+function inputNumber(num) {
+  if (shouldResetInput) {
+    currentInput = num;
+    shouldResetInput = false;
+  } else {
+    // 避免出现多个前导 0
+    currentInput = currentInput === '0' ? num : currentInput + num;
+  }
+  updateDisplay();
+}
+
+/**
+ * 输入小数点
+ */
+function inputDecimal() {
+  if (shouldResetInput) {
+    currentInput = '0.';
+    shouldResetInput = false;
+  } else if (!currentInput.includes('.')) {
+    currentInput += '.';
+  }
+  updateDisplay();
+}
+
+/**
+ * 执行计算
+ * @param {number} a
+ * @param {number} b
+ * @param {string} op
+ * @returns {number}
+ */
+function calculate(a, b, op) {
+  switch (op) {
+    case '+': return a + b;
+    case '-': return a - b;
+    case '×': return a * b;
+    case '÷':
+      if (b === 0) return NaN; // 除零处理
+      return a / b;
+    default: return b;
+  }
+}
+
+/**
+ * 选择运算符
+ * @param {string} op
+ */
+function chooseOperator(op) {
+  const inputValue = parseFloat(currentInput);
+
+  // 连续按运算符时，先计算前一步
+  if (previousValue !== null && currentOperator && !shouldResetInput) {
+    const result = calculate(previousValue, inputValue, currentOperator);
+    if (isNaN(result)) {
+      currentInput = '错误';
+      previousValue = null;
+      currentOperator = null;
+      shouldResetInput = true;
+      updateDisplay();
+      return;
+    }
+    previousValue = result;
+    currentInput = formatNumber(result);
+  } else {
+    previousValue = inputValue;
+  }
+
+  currentOperator = op;
+  shouldResetInput = true;
+  updateDisplay();
+}
+
+/**
+ * 按等号计算结果
+ */
+function pressEquals() {
+  if (previousValue === null || currentOperator === null) return;
+
+  const inputValue = parseFloat(currentInput);
+  const result = calculate(previousValue, inputValue, currentOperator);
+
+  if (isNaN(result)) {
+    currentInput = '错误';
+  } else {
+    currentInput = formatNumber(result);
+  }
+
+  previousValue = null;
+  currentOperator = null;
+  shouldResetInput = true;
+  updateDisplay();
+}
+
+/**
+ * 清除所有状态
+ */
+function clearAll() {
+  currentInput = '0';
+  previousValue = null;
+  currentOperator = null;
+  shouldResetInput = false;
+  updateDisplay();
+}
+
+/**
+ * 格式化数字，避免过长的小数
+ * @param {number} num
+ * @returns {string}
+ */
+function formatNumber(num) {
+  if (!isFinite(num)) return '错误';
+  // 保留最多 10 位有效数字，去掉多余的 0
+  return parseFloat(num.toPrecision(12)).toString();
+}
+
+// ===== 事件绑定 =====
+document.querySelector('.keys').addEventListener('click', (e) => {
+  const btn = e.target.closest('button');
+  if (!btn) return;
+
+  const action = btn.dataset.action;
+
+  switch (action) {
+    case 'number':
+      inputNumber(btn.dataset.value);
+      break;
+    case 'decimal':
+      inputDecimal();
+      break;
+    case 'operator':
+      chooseOperator(btn.dataset.op);
+      break;
+    case 'equals':
+      pressEquals();
+      break;
+    case 'clear':
+      clearAll();
+      break;
+  }
+});
+
+// ===== 键盘支持 =====
+document.addEventListener('keydown', (e) => {
+  const key = e.key;
+
+  if (/^[0-9]$/.test(key)) {
+    inputNumber(key);
+  } else if (key === '.') {
+    inputDecimal();
+  } else if (key === '+' || key === '-' || key === '*' || key === '/') {
+    const map = { '*': '×', '/': '÷', '+': '+', '-': '-' };
+    chooseOperator(map[key]);
+  } else if (key === 'Enter' || key === '=') {
+    e.preventDefault();
+    pressEquals();
+  } else if (key === 'Escape' || key.toLowerCase() === 'c') {
+    clearAll();
+  } else if (key === 'Backspace') {
+    // 退格删除
+    if (currentInput.length > 1 && currentInput !== '错误') {
+      currentInput = currentInput.slice(0, -1);
+    } else {
+      currentInput = '0';
+    }
+    updateDisplay();
+  }
+});
+
+// ===== 初始化 =====
+updateDisplay();