JavaScript，如果不是的话，速记更好的代码

如何更好地执行此代码：

let styleDaysCount = {'color': 'green'}
user.demo && user.days_count < 3 ? styleDaysCount = {'color': 'red'} : styleDaysCount = {'color': 'green'}

---

可以将条件放在对象文本中

let styleDaysCount = {
    color: (user.demo && user.days_count < 3) ? 'red' : 'green'
}

let styledaysunt={
颜色：（user.demo&&user.days\u count<3）？“红色”：“绿色”
}

您也可以这样做：

const color = user.demo && user.days_count < 3 ? 'red' : 'green';
const styleDaysCount = { color };

const color=user.demo&&user.days\u计数<3？“红色“：“绿色”；
const styledayscont={color}；

您只需分配三元函数的结果即可

---

const styledayscont=user.demo&&user.days\u计数<3？{'color'：'red'}:{'color'：'green'}

IMHO if/else的功能实现非常优雅和精确：

实施

export const conditionally = (config) => (props) => {
  return config.if(props) ? 
    config.then(props) : config.else(props);
};

不带功能性if/else的用法

function getCarConfig(car) {
  let description;
  let newPrice;

  if (car.rating > 4) {
    description = "good car";
    newPrice = car.price + 1000 * car.rating;
  } else {
    description = "bad car";
    newPrice = car.price;
  }

  return {
    description,
    newPrice,
  }
}

const hasGoodRating = rating => rating > 4;

const priceChange = conditionally({
  if: hasGoodRating,
  then: rating => 1000 * rating,
  else: () => 1000,
});

const getDescription = conditionally({
  if: hasGoodRating,
  then: () => "good car",
  else: () => "bad car",
});

function getCarConfig (car) {
  return {
    newPrice: priceChange(car.rating) + car.price,
    description: getDescription(car.rating)
  }
}

使用功能性if/else

function getCarConfig(car) {
  let description;
  let newPrice;

  if (car.rating > 4) {
    description = "good car";
    newPrice = car.price + 1000 * car.rating;
  } else {
    description = "bad car";
    newPrice = car.price;
  }

  return {
    description,
    newPrice,
  }
}

const hasGoodRating = rating => rating > 4;

const priceChange = conditionally({
  if: hasGoodRating,
  then: rating => 1000 * rating,
  else: () => 1000,
});

const getDescription = conditionally({
  if: hasGoodRating,
  then: () => "good car",
  else: () => "bad car",
});

function getCarConfig (car) {
  return {
    newPrice: priceChange(car.rating) + car.price,
    description: getDescription(car.rating)
  }
}

---

Ref:

为什么不想使用

if

语句？尝试使用速记if-else。但我不知道现在是否有可能使用更短的代码。它被称为

三元运算

，fyiw人们为什么讨厌if语句？

const styleDaysCount={color:user.demo&&user.days\u count<3？'red'：'green'}

为什么投票被否决？我不是，我只是对我觉得好的东西投了票，永远不要投票否决正确答案。有人投票否决了所有答案哈哈，甚至我的问题。。