原生JavaScript实现简易网页计算器

<!DOCTYPE html>
<html lang="zh-CN">
 
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
 
        .cal {
            width: 420px;
            margin: 100px auto;
            background-color: #E6E6E6;
 
            padding: 2px;
            overflow: hidden;
        }
 
 
        .show {
            position: relative;
            width: 416px;
            height: 120px;
 
            font-size: 50px;
            line-height: 50px;
            font-weight: 700;
        }
 
        .show button {
            display: none;
 
            position: absolute;
            top: -2px;
            right: -2px;
 
            width: 60px;
            height: 40px;
            line-height: 40px;
            text-align: center;
            border: transparent;
            background-color: #E6E6E6;
 
            font-size: 30px;
            font-weight: 100;
            cursor: pointer;
        }
 
        .show button:hover {
            background-color: #e81123;
            color: #f0f0f0
        }
 
        .res,
        .left,
        .right {
            position: absolute;
            bottom: 0;
 
            height: 60px;
            line-height: 60px;
            padding: 0 3px;
        }
 
        .res {
            right: 0;
            /* width: 100%; */
 
            text-align: right;
        }
 
        .left {
            display: none;
            background-color: #E6E6E6;
        }
 
        .right {
            display: none;
            right: 0;
            background-color: #E6E6E6;
        }
 
        .left:hover,
        .right:hover {
            color: #2e8eda;
        }
 
        .keyboard {
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
        }
 
 
 
        .btn {
            display: flex;
            justify-content: center;
 
            width: 100px;
            height: 60px;
            line-height: 60px;
            margin: 2px;
 
            background-color: #f0f0f0;
            border: transparent;
 
            font-size: large;
        }
 
        .btn:hover {
            background-color: #d6d6d6;
        }
 
        .digital {
            background-color: #fafafa;
            font-weight: 700;
        }
 
        .equal {
            background-color: #8abae0;
        }
 
        .equal:hover {
            background-color: #4599db;
        }
    </style>
</head>
 
<body>
 
    <div class="cal">
        <div class="show">
            <button class="close">×</button>
            <div class="res">0</div>
            <div class="left">&lt;</div>
            <div class="right">&gt;</div>
        </div>
        <div class="keyboard">
            <!-- 0 -->
            <button class="btn percent">%</button>
            <!-- 1 -->
            <button class="btn clearOne">CE</button>
            <!-- 2 -->
            <button class="btn clearAll">C</button>
            <!-- 3 -->
            <button class="btn back">del</button>
            <!-- 4 -->
            <button class="btn div1">1/x</button>
            <!-- 5 -->
            <button class="btn square">x²</button>
            <!-- 6 -->
            <button class="btn sqrt">²√x</button>
            <!-- 7 -->
            <button class="btn div">÷</button>
            <!-- 8 -->
            <button class="btn digital">7</button>
            <!-- 9 -->
            <button class="btn digital">8</button>
            <!-- 10 -->
            <button class="btn digital">9</button>
            <!-- 11 -->
            <button class="btn mul">x</button>
            <!-- 12 -->
            <button class="btn digital">4</button>
            <!-- 13 -->
            <button class="btn digital">5</button>
            <!-- 14 -->
            <button class="btn digital">6</button>
            <!-- 15 -->
            <button class="btn sub">-</button>
            <!-- 16 -->
            <button class="btn digital">1</button>
            <!-- 17 -->
            <button class="btn digital">2</button>
            <!-- 18 -->
            <button class="btn digital">3</button>
            <!-- 19 -->
            <button class="btn add">+</button>
            <!-- 20 -->
            <button class="btn neg">+/-</button>
            <!-- 21 -->
            <button class="btn digital">0</button>
            <!-- 22 -->
            <button class="btn digital">.</button>
            <!-- 23 -->
            <button class="btn equal">=</button>
        </div>
    </div>
    <script src="./计算机.js"></script>
</body>
 
</html>

const bt = document.querySelectorAll('.keyboard button')
const close = document.querySelector('.close')
const res = document.querySelector('.res')
//当点击的数字的时候
let k = 0
let one
let two
function arr(num) {
    bt[num].onclick = function () {
        res.innerText += bt[num].innerText
        res.innerText = parseFloat(res.innerText)
        // console.log(one)
 
    }
}
//小数点
//保留结果小数
function fn() {
    if (res.innerText.length > 8) {
        res.innerText = res.innerText.slice(0, 10)
    }
    if (res.innerText == 'NaN') {
        res.innerText = 0
    }
 
}
 
//当点击的是运算符号的时候
function symbol(str, fu) {
    bt[str].onclick = function () {
        k++
        if (k > 1) {
            return
        }
        one = parseFloat(res.innerText)
        // switch (fu) {
        //     case '+':
        //         one += one
        //         break;
        //     case '-':
        //         one -= one
        //         break;
        //     case '*':
        //         one *= one
        //         break;
        //     case '/':
        //         one /= one
        //         break;
        // }
        res.innerText = ''
        close.style.display = 'block'
        close.innerText = bt[str].innerText
        console.log(one)
    }
}
 
arr(21)
arr(18)
arr(17)
arr(16)
arr(14)
arr(13)
arr(12)
arr(10)
arr(9)
arr(8)
arr(22)
//运算符号
symbol(0)
symbol(7, '/')
symbol(11, '*')
symbol(15, '-')
symbol(19, '+')
console.log(bt[22].innerText)
bt[22].onclick = function () {
    res.innerText += bt[22].innerText
    console.log(565)
}
bt[23].onclick = function () {
    two = parseFloat(res.innerText)
    switch (close.innerText) {
        case '%':
            //toFixed(11)保留11位小数
            res.innerText = one % two
            k = 0
            break;
        case '+':
            res.innerText = one + two
            k = 0
            break;
        case '-':
            res.innerText = one - two
            k = 0
            break;
        case 'x':
            res.innerText = one * two
            k = 0
            break;
        case '÷':
            res.innerText = one / two
            k = 0
            break;
    }
    // console.log(res.innerText.length)
    fn()
 
 
}
bt[1].onclick = function () {
    res.innerText = ''
}
bt[2].onclick = function () {
    res.innerText = '0'
    close.innerText = 'x'
    close.style.display = ''
    one = 0
    two = 0
}
bt[3].onclick = function () {
    res.innerText = res.innerText.slice(0, res.innerText.length - 1)
    if (res.innerText.length === 0) {
        res.innerText = '0'
        return
    }
}
bt[4].onclick = function () {
    res.innerText = 1 / parseFloat(res.innerText)
    fn()
}
bt[5].onclick = function () {
    res.innerText = parseFloat(res.innerText) * parseFloat(res.innerText)
    fn()
}
 
bt[6].onclick = function () {
    res.innerText = Math.sqrt(parseFloat(res.innerText))
    fn()
}
bt[20].onclick = function () {
    res.innerText = 0 - parseFloat(res.innerText)
    fn()
}