原生JS实现简单的汇率转换问题

Posted 2021-02-20 陈太浪

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html代码

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8" />

    <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <meta http-equiv="X-UA-Compatible" content="ie=edge" /> <title>Exchange Rate Calculator</title>

    <link rel="stylesheet" href="style.css" />

</head>

<body>

<img src="money.png" alt="" class="money-img" />

<h1>Exchange Rate Calculator</h1>

<p>Choose the currency and the amounts to get the exchange rate</p>

<div class="container">

    <div class="currency">

        <select id="currency-one">

            <option value="AED">AED</option>

            <option value="ARS">ARS</option>

            <option value="AUD">AUD</option>

            <option value="BGN">BGN</option>

            <option value="BRL">BRL</option>

            <option value="BSD">BSD</option>

            <option value="CAD">CAD</option>

            <option value="CHF">CHF</option>

            <option value="CLP">CLP</option>

            <option value="CNY">CNY</option>

            <option value="COP">COP</option>

            <option value="CZK">CZK</option>

            <option value="DKK">DKK</option>

            <option value="DOP">DOP</option>

            <option value="EGP">EGP</option>

            <option value="EUR">EUR</option>

            <option value="FJD">FJD</option>

            <option value="GBP">GBP</option>

            <option value="GTQ">GTQ</option>

            <option value="HKD">HKD</option>

            <option value="HRK">HRK</option>

            <option value="HUF">HUF</option>

            <option value="IDR">IDR</option>

            <option value="ILS">ILS</option>

            <option value="INR">INR</option>

            <option value="ISK">ISK</option>

            <option value="JPY">JPY</option>

            <option value="KRW">KRW</option>

            <option value="KZT">KZT</option>

            <option value="MXN">MXN</option>

            <option value="MYR">MYR</option>

            <option value="NOK">NOK</option>

            <option value="NZD">NZD</option>

            <option value="PAB">PAB</option>

            <option value="PEN">PEN</option>

            <option value="php">PHP</option>

            <option value="PKR">PKR</option>

            <option value="PLN">PLN</option>

            <option value="PYG">PYG</option>

            <option value="RON">RON</option>

            <option value="RUB">RUB</option>

            <option value="SAR">SAR</option>

            <option value="SEK">SEK</option>

            <option value="SGD">SGD</option>

            <option value="THB">THB</option>

            <option value="TRY">TRY</option>

            <option value="TWD">TWD</option>

            <option value="UAH">UAH</option>

            <option value="USD" selected>USD</option>

            <option value="UYU">UYU</option>

            <option value="VND">VND</option>

            <option value="ZAR">ZAR</option>

        </select>

        <input type="number" id="amount-one" placeholder="0" value="1" />



    </div>

    <div class="swap-rate-container">

        <button class="btn" id="swap">

            Swap

        </button>

        <div class="rate" id="rate"></div>

    </div>

    <div class="currency">

        <select id="currency-two">

            <option value="AED">AED</option>

            <option value="ARS">ARS</option>

            <option value="AUD">AUD</option>

            <option value="BGN">BGN</option>

            <option value="BRL">BRL</option>

            <option value="BSD">BSD</option>

            <option value="CAD">CAD</option>

            <option value="CHF">CHF</option>

            <option value="CLP">CLP</option>

            <option value="CNY">CNY</option>

            <option value="COP">COP</option>

            <option value="CZK">CZK</option>

            <option value="DKK">DKK</option>

            <option value="DOP">DOP</option>

            <option value="EGP">EGP</option>

            <option value="EUR" selected>EUR</option>

            <option value="FJD">FJD</option>

            <option value="GBP">GBP</option>

            <option value="GTQ">GTQ</option>

            <option value="HKD">HKD</option>

            <option value="HRK">HRK</option>

            <option value="HUF">HUF</option>

            <option value="IDR">IDR</option>

            <option value="ILS">ILS</option>

            <option value="INR">INR</option>

            <option value="ISK">ISK</option>

            <option value="JPY">JPY</option>

            <option value="KRW">KRW</option>

            <option value="KZT">KZT</option>

            <option value="MXN">MXN</option>

            <option value="MYR">MYR</option>

            <option value="NOK">NOK</option>

            <option value="NZD">NZD</option>


            <option value="PAB">PAB</option>

            <option value="PEN">PEN</option>

            <option value="PHP">PHP</option>

            <option value="PKR">PKR</option>

            <option value="PLN">PLN</option>

            <option value="PYG">PYG</option>

            <option value="RON">RON</option>

            <option value="RUB">RUB</option>

            <option value="SAR">SAR</option>

            <option value="SEK">SEK</option>

            <option value="SGD">SGD</option>

            <option value="THB">THB</option>

            <option value="TRY">TRY</option>

            <option value="TWD">TWD</option>

            <option value="UAH">UAH</option>

            <option value="USD">USD</option>

            <option value="UYU">UYU</option>

            <option value="VND">VND</option>

            <option value="ZAR">ZAR</option>

        </select>

        <input type="number" id="amount-two" placeholder="0" /> </div>

</div>

<script src="script.js"></script>

</body>

</html>

css代码

:root {

    --primary-color: #5fbaa7;

}

*	{

    box-sizing: border-box;

}

body {

    background-color: #f4f4f4;

    font-family: Arial, Helvetica, sans-serif;

    display: flex;

    flex-direction: column;

    align-items: center;

    justify-content: center;
    height: 100vh;

    margin: 0;

    padding: 20px;

}

h1 {

    color: var(--primary-color);

}

p	{

    text-align: center;

}

.btn {

    color: #fff;

    background: var(--primary-color);

    cursor: pointer;

    border-radius: 5px;

    font-size: 12px;

    padding: 5px 12px;

}

.money-img {

    width: 150px;

}

.currency {

    padding: 40px 0;

    display: flex;

    align-items: center;

    justify-content: space-between;

}

.currency select {

    padding: 10px 20px 10px 10px;

    -moz-appearance: none;

    -webkit-appearance: none;

    appearance: none;

    border: 1px solid #dedede;

    font-size: 16px;

    background: transparent;

    background-image: url(‘data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2229 2.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%20000002%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E‘);

    background-position: right 10px top 50%, 0, 0;

    background-size: 12px auto, 100%;

    background-repeat: no-repeat;

    }

    .currency input {

    border: 0;

    background: transparent;

    font-size: 30px;

    text-align: right;

    }

    .swap-rate-container {

    display: flex;

    align-items: center;

    justify-content: space-between;

    }

    .rate {

    color: var(--primary-color);

    font-size: 14px;

    padding: 0 10px;

}

select:focus,

input:focus,

button:focus {

    outline: 0;

}

@media (max-width: 600px) {

    .currency input {

        width: 200px;

    }

}

javascript代码


// 获取货币1对象
let currencyEl_one = document.getElementById("currency-one");
// 获取货币2对象
let currencyEl_two = document.getElementById("currency-two");
// 获取货币1对应的汇率对象
let amountEl_one = document.getElementById("amount-one");
// 获取货币2对应的汇率对象
let amountEl_two = document.getElementById("amount-two");
// 获取提示框对应的对象
let rateEl = document.getElementById("rate");

// 检查初始状态下 是否需要换算汇率
getData();

// 货币2发生变化时 触发的事件
currencyEl_two.onchange = getData;

// 货币1发生变化时 触发的事件
currencyEl_one.onchange = getData;

// 获取按钮 货币1和货币2是否都有值
let btn = document.getElementById("swap");

// 点击交换按钮时 触发的事件
btn.onclick = function() {
    // console.log("!!!");
    let currency_one = currencyEl_one.value;
    let currency_two = currencyEl_two.value;
    // 定义临时变量
    let temp = currency_one;
    // 交换货币1和货币2的value
    currencyEl_one.value = currency_two;
    currencyEl_two.value = temp;
    // 并且交换货币1和货币2对应的汇率
    currency_one = currency_two;
    currency_two = temp;

    fetch(`https://api.exchangerate-api.com/v4/latest/${currency_one}`)
        .then(res => res.json())
        .then(data => {
            const rate = data.rates[currency_two];
            rateEl.innerText = `1 ${currency_one} = ${rate} ${currency_two}`;
            amountEl_two.value = (amountEl_one.value * rate).toFixed(2);
        });

};

// 得到汇率
function getData() {
        let currency_one = currencyEl_one.value;
        let currency_two = currencyEl_two.value;
        fetch(`https://api.exchangerate-api.com/v4/latest/${currency_one}`)
            .then(res => res.json())
            .then(data => {
                const rate = data.rates[currency_two];
                rateEl.innerText = `1 ${currency_one} = ${rate} ${currency_two}`;
                amountEl_two.value = (amountEl_one.value * rate).toFixed(2);

            });
}

运行效果

技术图片

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