简单计算器

工具 admin · 2026-08-29 · 使用 7
支持加减乘除的简洁计算器，手机和电脑均可使用。
简单计算器
放大后操作
纯前端工具，无后端代码
HTML
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
    <title>简单计算器</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            -webkit-tap-highlight-color: transparent;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #1e3c72, #2a5298);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 16px;
        }
        .calculator {
            background: #1a1a2e;
            border-radius: 24px;
            padding: 20px;
            width: 100%;
            max-width: 360px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.4);
        }
        .display {
            background: #0f0f1a;
            border-radius: 16px;
            padding: 20px;
            margin-bottom: 20px;
            text-align: right;
            min-height: 90px;
            display: flex;
            flex-direction: column;
            justify-content: flex-end;
            word-break: break-all;
            border: 1px solid #2a2a4a;
        }
        .expression {
            color: #8a8ab0;
            font-size: 16px;
            min-height: 24px;
            margin-bottom: 4px;
        }
        .result {
            color: #ffffff;
            font-size: 36px;
            font-weight: bold;
            line-height: 1.2;
        }
        .buttons {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 12px;
        }
        button {
            background: #16213e;
            border: none;
            border-radius: 16px;
            color: #ffffff;
            font-size: 22px;
            font-weight: 600;
            padding: 18px 0;
            cursor: pointer;
            transition: all 0.15s ease;
            box-shadow: 0 4px 8px rgba(0,0,0,0.3);
            user-select: none;
        }
        button:active {
            transform: scale(0.95);
            background: #1f3a5f;
        }
        .operator {
            background: #2d4a7a;
        }
        .operator:active {
            background: #3a5f96;
        }
        .equals {
            background: #e94560;
            color: white;
        }
        .equals:active {
            background: #ff5d78;
        }
        .clear {
            background: #b83232;
        }
        .clear:active {
            background: #d84545;
        }
        .backspace {
            background: #b83232;
        }
        .backspace:active {
            background: #d84545;
        }
        .zero {
            grid-column: span 2;
        }
        @media (max-width: 360px) {
            .calculator {
                padding: 12px;
            }
            .buttons {
                gap: 8px;
            }
            button {
                font-size: 18px;
                padding: 14px 0;
            }
            .result {
                font-size: 28px;
            }
        }
    </style>
</head>
<body>
    <div class="calculator">
        <div class="display">
            <div class="expression" id="expression">&nbsp;</div>
            <div class="result" id="result">0</div>
        </div>
        <div class="buttons">
            <button class="clear" onclick="clearAll()">C</button>
            <button class="backspace" onclick="backspace()">⌫</button>
            <button class="operator" onclick="addOperator('%')">%</button>
            <button class="operator" onclick="addOperator('/')">÷</button>
            
            <button onclick="addNumber('7')">7</button>
            <button onclick="addNumber('8')">8</button>
            <button onclick="addNumber('9')">9</button>
            <button class="operator" onclick="addOperator('*')">×</button>
            
            <button onclick="addNumber('4')">4</button>
            <button onclick="addNumber('5')">5</button>
            <button onclick="addNumber('6')">6</button>
            <button class="operator" onclick="addOperator('-')">-</button>
            
            <button onclick="addNumber('1')">1</button>
            <button onclick="addNumber('2')">2</button>
            <button onclick="addNumber('3')">3</button>
            <button class="operator" onclick="addOperator('+')">+</button>
            
            <button class="zero" onclick="addNumber('0')">0</button>
            <button onclick="addDot()">.</button>
            <button class="equals" onclick="calculate()">=</button>
        </div>
    </div>

    <script>
        let expression = '';
        let lastResult = null;
        const expressionEl = document.getElementById('expression');
        const resultEl = document.getElementById('result');

        function updateDisplay() {
            expressionEl.textContent = expression || '&nbsp;';
            if (expression) {
                // 尝试实时计算中间结果
                try {
                    const val = evalExpression(expression);
                    if (val !== null && isFinite(val)) {
                        resultEl.textContent = formatNumber(val);
                    } else {
                        resultEl.textContent = '0';
                    }
                } catch(e) {
                    resultEl.textContent = '0';
                }
            } else {
                resultEl.textContent = (lastResult !== null) ? formatNumber(lastResult) : '0';
            }
        }

        function formatNumber(num) {
            if (Number.isInteger(num)) return num.toString();
            // 避免浮点误差
            const rounded = Math.round(num * 1e10) / 1e10;
            return rounded.toString();
        }

        function evalExpression(expr) {
            // 简单安全的表达式求值，只允许数字和运算符
            if (!/^[0-9.\s+\-*/%]+$/.test(expr)) return null;
            try {
                // 处理百分号: 将 x% 替换为 x/100
                let cleanExpr = expr;
                // 使用 Function 代替 eval (同样有风险，但这里输入已过滤)
                // 更安全：手动解析
                return parseAndEval(cleanExpr);
            } catch(e) {
                return null;
            }
        }

        // 手动解析四则运算，避免 eval 风险
        function parseAndEval(expr) {
            // 移除空格
            expr = expr.replace(/\s+/g, '');
            if (!expr) return null;
            
            // 解析为 token
            const tokens = [];
            let numBuffer = '';
            for (let i = 0; i < expr.length; i++) {
                const ch = expr[i];
                if ('0123456789.'.indexOf(ch) !== -1) {
                    numBuffer += ch;
                } else if ('+-*/%'.indexOf(ch) !== -1) {
                    if (numBuffer === '' && (ch === '-' || ch === '+') && tokens.length === 0) {
                        numBuffer = ch;
                        continue;
                    }
                    if (numBuffer !== '') {
                        tokens.push(parseFloat(numBuffer));
                        numBuffer = '';
                    }
                    tokens.push(ch);
                } else {
                    return null;
                }
            }
            if (numBuffer !== '') tokens.push(parseFloat(numBuffer));
            else return null;

            // 处理百分号: 将 a% 变为 a/100
            for (let i = 0; i < tokens.length; i++) {
                if (tokens[i] === '%') {
                    if (i > 0 && typeof tokens[i-1] === 'number') {
                        tokens[i-1] = tokens[i-1] / 100;
                        tokens.splice(i, 1);
                        i--;
                    } else {
                        return null;
                    }
                }
            }

            // 先乘除后加减
            const stack = [tokens[0]];
            for (let i = 1; i < tokens.length; i += 2) {
                const op = tokens[i];
                const num = tokens[i+1];
                if (num === undefined) return null;
                if (op === '*') {
                    stack.push(stack.pop() * num);
                } else if (op === '/') {
                    if (num === 0) return Infinity;
                    stack.push(stack.pop() / num);
                } else {
                    stack.push(op);
                    stack.push(num);
                }
            }
            // 处理加减
            let result = stack[0];
            for (let i = 1; i < stack.length; i += 2) {
                const op = stack[i];
                const num = stack[i+1];
                if (op === '+') result += num;
                else if (op === '-') result -= num;
            }
            return result;
        }

        function addNumber(num) {
            // 避免多个前导零
            if (expression === '0' && num === '0') return;
            if (expression === '0') {
                expression = num;
            } else {
                expression += num;
            }
            updateDisplay();
        }

        function addOperator(op) {
            if (!expression && lastResult !== null) {
                // 从结果继续计算
                expression = formatNumber(lastResult) + op;
                lastResult = null;
            } else if (expression) {
                // 替换末尾运算符
                const lastChar = expression[expression.length - 1];
                if ('+-*/%'.indexOf(lastChar) !== -1) {
                    expression = expression.slice(0, -1) + op;
                } else {
                    expression += op;
                }
            } else {
                // 无输入，忽略
                return;
            }
            updateDisplay();
        }

        function addDot() {
            if (!expression) {
                expression = '0.';
            } else {
                // 检查当前数字是否已有小数点
                const parts = expression.split(/[+\-*/%]/);
                const current = parts[parts.length - 1];
                if (current.includes('.')) return;
                expression += '.';
            }
            updateDisplay();
        }

        function calculate() {
            if (!expression) return;
            const result = parseAndEval(expression);
            if (result === null || result === undefined) {
                resultEl.textContent = '错误';
                return;
            }
            if (!isFinite(result)) {
                resultEl.textContent = '错误';
                expression = '';
                lastResult = null;
                updateDisplay();
                return;
            }
            const formatted = formatNumber(result);
            expression = '';
            lastResult = formatted;
            expressionEl.textContent = '';
            resultEl.textContent = formatted;
        }

        function clearAll() {
            expression = '';
            lastResult = null;
            expressionEl.textContent = '&nbsp;';
            resultEl.textContent = '0';
        }

        function backspace() {
            if (expression.length > 0) {
                expression = expression.slice(0, -1);
                updateDisplay();
            } else if (lastResult !== null) {
                lastResult = null;
                resultEl.textContent = '0';
            }
        }

        // 键盘支持
        document.addEventListener('keydown', function(e) {
            const key = e.key;
            if (key >= '0' && key <= '9') {
                addNumber(key);
            } else if (key === '.') {
                addDot();
            } else if (key === '+' || key === '-' || key === '*' || key === '/') {
                addOperator(key);
            } else if (key === '%') {
                addOperator('%');
            } else if (key === 'Enter' || key === '=') {
                calculate();
            } else if (key === 'Backspace') {
                backspace();
            } else if (key === 'Escape') {
                clearAll();
            }
            e.preventDefault();
        });

        updateDisplay();
    </script>
</body>
</html>
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简单计算器

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