原生JS怎么实现汇率转换功能

<!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" rel="external nofollow" /> </head> <body> <img src="money.png" class="money-img" /> <h2>Exchange Rate Calculator</h2> <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>

: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; } h2 { 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; } }

// 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); }); }

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