如何向已经包含 .map 和 .filter 的箭头函数添加 if 、 else if 和 else 条件？

Question

下面的函数需要设置选项数组中选定元素的option.value。如果选择了 3 个或更多选项，则需要将其设置为每个 1.50 美元，如果选择 6 个或更多选项，则每个选项需要设置为 1.00 美元。现在它就像一个魅力，因为它只是从数组中获取 options.value 并将其设置为当前价格，但是我需要将此折扣功能添加到我的函数中。我怎样才能做到这一点？

我目前的工作功能没有折扣。

private getSelectedOptions(options) {
      return (options || []).filter(x => x.selected).map
         (option => ({ name: option.name, value: option.value || 0 }));
 }

选项数组

 "options": [
    {
      "name": "Red Pepper",
      "selected": false,
      "value": 2.00
    },
    {
      "name": "Garlic",
      "selected": false,
       "value": 2.00

    },
    {
      "name": "Cheese blend",
      "selected": false,
       "value": 2.00
    },
     {
      "name": "pineapple",
      "selected": false,
       "value": 2.00
    },
     {
      "name": "bacon",
      "selected": false,
       "value": 2.00
    },
    {
      "name": "green pepper",
      "selected": false,

    }

Answer 1

箭头函数是一个普通的JavaScript函数，所以，如果你去掉“()”，只把“{}”变成一个函数，带主体，return一个对象再次，return {}

Answer 2

首先将映射数组保存在一个变量中，这样您就可以检查它 length 以确定所需的价格：

private getSelectedOptions(options) {
  const selectedItems = (options || []).filter(x => x.selected);
  const price = selectedItems.length >= 6
    ? 1
    : selectedItems.length >= 3
      ? 1.5
      : 2;
  return selectedItems.map(
    option => ({ name: option.name, value: option.value ? price : 0 })
  );
 }

const getSelectedOptions = (options) => {
  const selectedItems = (options || []).filter(x => x.selected);
  const price = selectedItems.length >= 6
    ? 1
    : selectedItems.length >= 3
      ? 1.5
      : 2;
  return selectedItems.map(
    option => ({ name: option.name, value: option.value ? price : 0 })
  );
};
 
 const options = [
  {
    "name": "Red Pepper",
    "selected": true,
    "value": 2.00
  },
  {
    "name": "Garlic",
    "selected": true,
     "value": 2.00

  },
  {
    "name": "Cheese blend",
    "selected": true,
     "value": 2.00
  },
   {
    "name": "pineapple",
    "selected": false,
     "value": 2.00
  },
   {
    "name": "bacon",
    "selected": false,
     "value": 2.00
  },
  {
    "name": "green pepper",
    "selected": true,

  }
];

console.log(getSelectedOptions(options));

如果选项可以有不同的值，找出一个乘以它们的因子，例如 1 或 0.75 或 5:

const getSelectedOptions = (options) => {
  const selectedItems = (options || []).filter(x => x.selected);
  const factor = selectedItems.length >= 6
    ? 0.5
    : selectedItems.length >= 3
      ? 0.75
      : 1;
  return selectedItems.map(
    option => ({ name: option.name, value: option.value * factor })
  );
};
 
 const options = [
  {
    "name": "Red Pepper",
    "selected": true,
    "value": 5.00
  },
  {
    "name": "Garlic",
    "selected": true,
     "value": 2.00

  },
  {
    "name": "Cheese blend",
    "selected": true,
     "value": 2.00
  },
   {
    "name": "pineapple",
    "selected": false,
     "value": 2.00
  },
   {
    "name": "bacon",
    "selected": false,
     "value": 2.00
  },
  {
    "name": "green pepper",
    "selected": true,

  }
];

console.log(getSelectedOptions(options));

如何向已经包含 .map 和 .filter 的箭头函数添加 if 、 else if 和 else 条件？

How do I add an if , else if, else condition to my arrow function which includes .map and .filter already?

javascript

arrays

if-statement

arrow-functions

array.prototype.map