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html如何计算器

要创建一个HTML计算器,你需要使用HTML、CSS和JavaScript,以下是详细步骤:

1、创建HTML结构

我们需要创建一个HTML文件,然后在其中添加一个表单,用于显示计算器的输入框和按钮。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF8">
    <meta name="viewport" content="width=devicewidth, initialscale=1.0">
    <title>简易计算器</title>
</head>
<body>
    <form id="calculator">
        <input type="text" id="display" readonly>
        <br>
        <button type="button" onclick="clearDisplay()">C</button>
        <button type="button" onclick="appendNumber(7)">7</button>
        <button type="button" onclick="appendNumber(8)">8</button>
        <button type="button" onclick="appendNumber(9)">9</button>
        <button type="button" onclick="appendOperator('+')">+</button>
        <br>
        <button type="button" onclick="appendNumber(4)">4</button>
        <button type="button" onclick="appendNumber(5)">5</button>
        <button type="button" onclick="appendNumber(6)">6</button>
        <button type="button" onclick="appendOperator('')"></button>
        <br>
        <button type="button" onclick="appendNumber(1)">1</button>
        <button type="button" onclick="appendNumber(2)">2</button>
        <button type="button" onclick="appendNumber(3)">3</button>
        <button type="button" onclick="appendOperator('*')">*</button>
        <br>
        <button type="button" onclick="appendNumber(0)">0</button>
        <button type="button" onclick="appendOperator('.')">.</button>
        <button type="button" onclick="calculateResult()">=</button>
        <button type="button" onclick="appendOperator('/')">/</button>
    </form>
    <script src="calculator.js"></script>
</body>
</html>

2、编写CSS样式

接下来,我们需要为计算器添加一些基本的样式,在<head>标签内添加以下代码:

<style>
    body {
        fontfamily: Arial, sansserif;
        display: flex;
        justifycontent: center;
        alignitems: center;
        height: 100vh;
        margin: 0;
    }
    form {
        border: 1px solid #ccc;
        padding: 20px;
        borderradius: 5px;
    }
    input {
        width: 100%;
        marginbottom: 10px;
        textalign: right;
    }
    button {
        width: 22%;
        margin: 1%;
        fontsize: 18px;
    }
</style>

3、编写JavaScript代码

我们需要编写JavaScript代码来处理计算器的功能,创建一个名为calculator.js的文件,并在其中添加以下代码:

const display = document.getElementById('display');
let currentInput = '';
let operator = null;
let firstOperand = null;
let shouldReset = false;
function appendNumber(number) {
    if (shouldReset) {
        resetCalculator();
    }
    currentInput += number;
    display.value = currentInput;
}
function appendOperator(op) {
    if (operator !== null) {
        calculateResult();
    }
    firstOperand = parseFloat(currentInput);
    operator = op;
    currentInput = '';
}
function clearDisplay() {
    currentInput = '';
    operator = null;
    firstOperand = null;
    shouldReset = false;
    display.value = '';
}
function calculateResult() {
    const secondOperand = parseFloat(currentInput);
    let result = 0;
    switch (operator) {
        case '+':
            result = firstOperand + secondOperand;
            break;
        case '':
            result = firstOperand secondOperand;
            break;
        case '*':
            result = firstOperand * secondOperand;
            break;
        case '/':
            result = firstOperand / secondOperand;
            break;
        default:
            return;
    }
    display.value = result;
    currentInput = '';
    operator = null;
    firstOperand = null;
    shouldReset = true;
}

现在,你可以在浏览器中打开HTML文件,查看并使用你的简易计算器了。

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