有没有办法在打字稿中对具有可为空属性的数组进行排序？

Question

这是我的代码：

export function getExpertTitle(
  experiences: Array<{
    title?: string | null;
    description?: string | null;
    endDate?: Date | null;
  }> | null
) {
  const emptyExperience = {
    title: null,
    description: null,
    endDate: null
  };

  let currentExperience = experiences && experiences[0];
  
  // Here is were i start to have the error
  // Object is possibly 'null' or 'undefined'.ts(2533)  

  for (let i = 0, l = experiences && experiences.length; i < (!isNullOrUndefined(l) && l); i++) {
    if (isNullOrUndefined(experiences && experiences[i].endDate)) {
      currentExperience = experiences && experiences[i];
    } else if ((!isNullOrUndefined(currentExperience) && currentExperience.endDate.getTime()) > Date.now()) {
      currentExperience = experiences && experiences[i];
    }
  }

所以，我想做的是比较 experiences 数组并使用 endDate 属性按日期对它们进行排序，我想将 currentExperience 设置为最新体验。此外，如果 endDate 属性是 'null' 体验仍在进行中，则默认为 currentExperience。

我原以为 for 循环看起来像这样，但我仍然收到错误消息：

  for (let i = 0, l = experiences.length; i < l; i++) {
    if (isNullOrUndefined(experiences[i].endDate)){
      currentExperience = experiences && experiences[i];
      break;
    }
    else if (experiences[i].endDate?.getTime() > currentExperience.endDate.getTime()) {
      currentExperience = experiences && experiences[i];
    }
  }

我仍在努力解决这个问题，如果我找到解决方案，我会post。同时，如有任何意见，我们将不胜感激。

Answer 1

出现此错误的原因是数组的类型定义表明任何条目都可能为空：

experiences: Array<{
    title?: string | null;
    description?: string | null;
    endDate?: Date | null;
  }> | null // <------------------ HERE

要过滤掉 null 值，您可以使用

experiences.filter(x => x !== null) as Array<{
  title?: string | null;
  description?: string | null;
  endDate?: Date | null; }> // array cannot contain null, only objects with null properties

但是根据你的代码所做的，我认为你更喜欢在你的 for 循环中使用这样的东西：

  for (let i = 0, l = experiences.length; i < l; i++) {
    // below is now true if the object is null
    if (isNullOrUndefined(experiences && experiences[i] && experiences[i].endDate)){
      currentExperience = experiences && experiences[i];
      break;
    }
    // ...
  }

有没有办法在打字稿中对具有可为空属性的数组进行排序？

Is there a way to sort an array with nullable properties in typescript?

arrays

sorting

null

typescript