JavaScript实现计算器的多种方式

AndersonHJB原创2023年2月25日大约 3 分钟...约 1007 字

你好，我是悦创。

接下来，为你分享多种计算器。

1. 界面一

html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Calculator</title>
    <style>
        label {
            display: inline-block;
            width: 80px;
            text-align: right;
        }

        input[type=number] {
            width: 100px;
            box-sizing: border-box;
            padding: 5px;
        }

        select {
            width: 50px;
            box-sizing: border-box;
            padding: 5px;
        }

        #equal {
            width: 50px;
            font-size: 20px;
        }
    </style>
    <script src="calculator.js"></script>
</head>
<body>
<label for="number1">Number 1:</label>
<input type="number" id="number1">

<select id="operation">
    <option value="add">+</option>
    <option value="subtract">-</option>
    <option value="multiply">*</option>
    <option value="divide">/</option>
</select>

<label for="number2">Number 2:</label>
<input type="number" id="number2">

<button id="equal" onclick="calculate()">=</button>

<span id="output"></span>
</body>
</html>

calculator.js

function calculate() {
    const num1 = parseInt(document.getElementById("number1").value);
    const num2 = parseInt(document.getElementById("number2").value);
    const operation = document.getElementById("operation").value;
    let result;
    switch (operation) {
        case "add":
            result = num1 + num2;
            break;
        case "subtract":
            result = num1 - num2;
            break;
        case "multiply":
            result = num1 * num2;
            break;
        case "divide":
            result = num1 / num2;
            break;
    }
    document.getElementById("output").textContent = result;
}

2. 界面二

html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Calculator</title>
    <style>
        input[type=number] {
            width: 100px;
            box-sizing: border-box;
            padding: 5px;
        }

        select {
            width: 50px;
            box-sizing: border-box;
            padding: 5px;
        }

        #equal {
            width: 50px;
            font-size: 20px;
        }
    </style>
    <script src="calculator.js"></script>
</head>
<body>
<input type="number" id="number1">

<select id="operation">
    <option value="add">+</option>
    <option value="subtract">-</option>
    <option value="multiply">*</option>
    <option value="divide">/</option>
</select>

<input type="number" id="number2">

<button id="equal" onclick="calculate()">=</button>

<span id="output"></span>
</body>
</html>

calculator.js

function calculate() {
    const num1 = parseInt(document.getElementById("number1").value);
    const num2 = parseInt(document.getElementById("number2").value);
    const operation = document.getElementById("operation").value;
    let result;
    switch (operation) {
        case "add":
            result = num1 + num2;
            break;
        case "subtract":
            result = num1 - num2;
            break;
        case "multiply":
            result = num1 * num2;
            break;
        case "divide":
            result = num1 / num2;
            break;
    }
    document.getElementById("output").textContent = result;
}

3. 界面三

html

<!DOCTYPE html>
<html>
<head>
    <title>Calculator</title>
    <meta charset="UTF-8">
    <style>
        #calculator {
            display: inline-block;
            border: 1px solid black;
            padding: 20px;
        }
        input[type="text"], select, input[type="button"] {
            padding: 10px;
            font-size: 16px;
        }
        input[type="button"] {
            background-color: #4CAF50;
            color: white;
            border: none;
            cursor: pointer;
            margin-left: 10px;
        }
        input[type="button"]:hover {
            background-color: #3E8E41;
        }
        #output {
            display: inline-block;
            font-size: 20px;
            padding: 10px;
            border: 1px solid black;
            margin-left: 10px;
        }
    </style>
</head>
<body>
<div id="calculator">
    <input type="text" id="number1" placeholder="Enter number 1">
    <select id="operation">
        <option value="add">+</option>
        <option value="subtract">-</option>
        <option value="multiply">*</option>
        <option value="divide">/</option>
    </select>
    <input type="text" id="number2" placeholder="Enter number 2">
    <input type="button" id="equal" value="=">
    <span id="output"></span>
</div>

<script>
    // Get DOM elements
    const number1Input = document.getElementById('number1');
    const number2Input = document.getElementById('number2');
    const operationSelect = document.getElementById('operation');
    const equalButton = document.getElementById('equal');
    const outputSpan = document.getElementById('output');

    // Add event listener to equal button
    equalButton.addEventListener('click', () => {
        // Get input values
        const number1 = Number(number1Input.value);
        const number2 = Number(number2Input.value);
        const operation = operationSelect.value;

        // Calculate result
        let result;
        switch (operation) {
            case 'add':
                result = number1 + number2;
                break;
            case 'subtract':
                result = number1 - number2;
                break;
            case 'multiply':
                result = number1 * number2;
                break;
            case 'divide':
                result = number1 / number2;
                break;
        }

        // Display result
        outputSpan.textContent = result;
    });
</script>
</body>
</html>

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