Question

我正在构建货币转换器应用。如何将这段代码变成箭头函数populateCurrencies？

currencies.forEach(function populateCurrencies (currency) {
    var option = document.createElement('option');
    option.value = currency.id;
    option.innerHTML = currency.name;
    selector.appendChild(option)
});

Answer 1

populateCurrencies = () => {
    return currencies.forEach(function populateCurrencies (currency) {
        var option = document.createElement('option');
        option.value = currency.id;
        option.innerHTML = currency.name;
        selector.appendChild(option)
    });

Answer 2

您可以像这样内联替换它：

currencies.forEach(currency => {
    var option = document.createElement('option');
    option.value = currency.id;
    option.innerHTML = currency.name;
    selector.appendChild(option);
});

由于只有一个自变量，因此可以省略该自变量周围的括号。如果有两个参数，则需要使用括号，例如(currency, someOtherArg) => {...

Answer 3

这是您要找的吗？

var currencies = [{
  id: 0,
  name: "euro"
}, {
  id: 1,
  name: "usd"
}];
var selector = document.querySelector("#selector");


currencies.forEach(currency => {
  var option = document.createElement('option');
  option.value = currency.id;
  option.innerHTML = currency.name;
  selector.appendChild(option);
});

<select id="selector"></select>

您也可以改为：

var currencies = [{
  id: 0,
  name: "euro"
}, {
  id: 1,
  name: "usd"
}];
var selector = document.querySelector("#selector");


selector.innerHTML = currencies.map(currency => `<option value=${currency.id}>${currency.name}</option>`).join("");

<select id="selector"></select>

如果要将整个forEach转换为箭头函数，可以执行以下操作：

var currencies = [{
  id: 0,
  name: "euro"
}, {
  id: 1,
  name: "usd"
}];
var selector = document.querySelector("#selector");


var populateCurrencies = () => {
  currencies.forEach(currency => {
    var option = document.createElement('option');
    option.value = currency.id;
    option.innerHTML = currency.name;
    selector.appendChild(option);
  });
};

populateCurrencies();

<select id="selector"></select>

尽管如此，您可以只使用普通函数。

如何使此代码段成为箭头函数

3 个答案: