javascript - merge, combine, transform 2 different arrays of Objects

Question

I can't figure it out how to transform and combine 2 arrays of object.

I have this 2 arrays of objects:

const selectedCourse = [
    {
      "courseType": [5],
      "id": 26,
      "title": "Apple Tart with Apricot Glaze",
  },
  {
    "courseType": [3],
    "id": 16,
    "title": "Classic Caesar Salad",
},
{
  "courseType": [1,2],
  "id": 10,
  "title": "Lobster Bisque",
},
{
  "courseType": [3],
  "id": 16,
  "title": "Classic Caesar Salad",
},
]

const courseTypes = [
{name: "Hors d'oeuvres", id: 0},
 {name: "Soup", id: 1},
 {name: "Fish", id: 2},
 {name: "Salad", id: 3},
 {name: "Main course", id: 4},
 {name: "Dessert", id: 5}
]

The courseType property inside the first JSON is an array of numbers that corresponds to courseTypes index and property id in the second JSON.

The result for this case should be this:

const result = [
  {
    courseType: 1,
    courseName: "Soup",
    courses: [
      {
        "courseType": [1,2],
        "id": 10,
        "title": "Lobster Bisque",
      }      
    ]
  },
  {
    courseType: 3,
    courseName: "Salad",
    courses: [
      {
        "courseType": [1,2],
        "id": 10,
        "title": "Lobster Bisque",
      }      
    ]
  },
  {
    courseType: 3,
    courseName: "Fish",
    courses: [
      {
        "courseType": [3],
        "id": 16,
        "title": "Classic Caesar Salad",
      },
      {
        "courseType": [3],
        "id": 16,
      },      
    ]
  },
  {
    courseType: 5,
    courseName: "Main course",
    courses: [
      {
        "courseType": [5],
        "id": 26,
        "title": "Apple Tart with Apricot Glaze",
      }
    ]
  }
]

The expected result have to combine the 2 arrays by filtering by courseType property.

Answer 1

Assuming, you want all items with selectedCourse, you could take a Map and collect all courses and later greate a new array out of the found values.

This solution includes Fish as well.

const
    selectedCourse = [{ courseType: [5], id: 26, title: "Apple Tart with Apricot Glaze" }, { courseType: [3], id: 16, title: "Classic Caesar Salad" }, { courseType: [1, 2], id: 10, title: "Lobster Bisque" }, { courseType: [3], id: 16, title: "Classic Caesar Salad" }],
    courseTypes = [{ name: "Hors d'oeuvres", id: 0 }, { name: "Soup", id: 1 }, { name: "Fish", id: 2 }, { name: "Salad", id: 3 }, { name: "Main course", id: 4 }, { name: "Dessert", id: 5 }],
    map = selectedCourse.reduce((m, o) => o.courseType.reduce((n, id) => n.set(id, [...(n.get(id) || []), o]), m), new Map),
    result = courseTypes.reduce(
        (r, { name: courseName, id: courseType }) => (map.get(courseType) || []).reduce((s, courses) => s.concat({ courseType, courseName, courses }), r),
        []
    );
   
console.log(result);

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