javascript - 将一个对象数组中的属性值映射到另一个对象数组 Javascript 中的属性

Question

我有两个对象数组:

courses = [ { _id: 999, courseCode: "Eng1" },
{ _id: 777, courseCode: "Sci1" },
{ _id: 666, courseCode: "Eng2" },
{ _id: 888, courseCode: "Sci2" }  ]

sectionCourses = [ { sectionCode: "1A", courseId: "999" },
{ sectionCode: "1A", courseId: "777" },
{ sectionCode: "2A", courseId: "666" }, 
{ sectionCode: "2A", courseId: "888" }  ]

我想过滤 courses 数组，使其只包含不在某个部分的类(class)。例如，如果我选择带有 sectionCode: "2A" 的部分，则 courses 数组应该只包含

courses = [ { _id: 999, courseCode: "Eng1" },
    { _id: 777, courseCode: "Sci1" },
    { _id: 888, courseCode: "Sci2" }  ]

我试过这样做:

 courses = courses.filter(c => !(sectionCourses.includes(c._id)))

但我知道这是不完整的，因为我不知道如何访问 sectionCourses 中的 courseId。

请帮忙。

Answer 1

您不能使用 .includes() 方法通过其 _id 查找整个对象，includes 比较整个对象而不搜索特定属性.

这里你可以做的是根据你提供的sectionCode得到一个courseIds数组，然后过滤掉他们的_id的类(class) 不存在于此 ids 数组中:

function getCourses(catCode) {

  var coursesIdstoIgnore = sectionCourses.filter(s => s.sectionCode === catCode).map(s => s.courseId);
  return courses.filter(c => coursesIdstoIgnore.indexOf(c["_id"].toString()) == -1);
}

演示:

var courses = [{
    _id: 999,
    courseCode: "Eng1"
  },
  {
    _id: 777,
    courseCode: "Sci1"
  },
  {
    _id: 666,
    courseCode: "Eng2"
  },
  {
    _id: 888,
    courseCode: "Sci2"
  }
];

var sectionCourses = [{
    sectionCode: "1A",
    courseId: "999"
  },
  {
    sectionCode: "1A",
    courseId: "777"
  },
  {
    sectionCode: "2A",
    courseId: "666"
  },
  {
    sectionCode: "2A",
    courseId: "888"
  }
];

function getCourses(catCode) {
  var cousesIdstoIgnore = sectionCourses.filter(s => s.sectionCode === catCode).map(s => s.courseId);
  console.log(cousesIdstoIgnore);

  return courses.filter(c => cousesIdstoIgnore.indexOf(c["_id"].toString()) == -1);

}

var results = getCourses("2A");


console.log(results);