Get a course for a student

studentCourses

const courses = [
  {
    "courseData" : [
      {
        "course" : {
          "day" : "Tuesday",
          "duration" : "10 weeks",
          "language" : "German",
          "location" : "Online",
          "startdate" : "12th January",
          "term" : "January",
          "time" : "17.30-18.30",
          "timeofday" : "Evening",
        },
        "courseID" : "JRNGETNXXOLTUV",
        "dates" : {
          "class1" : "12/01/2021",
        }
      }
    ]
  },
  {
    "courseData" : [
      {
        "course" : {
          "day" : "Wednesday",
          "duration" : "20 weeks",
          "language" : "Italian",
          "location" : "The Shed",
          "startdate" : "12th January",
          "term" : "January",
          "time" : "17.30-18.30",
          "timeofday" : "Midnight",
        },
        "courseID" : "GETNXXOLTUVABC",
        "dates" : {
          "class1" : "13/01/2021",
        }
      }
    ]
  },
];

const users = {
  'kwvjUSgZKXXfxxxxxxxxxxxxxxxxxx' : {
    courseID : "JRNGETNXXOLTUV",
    email : "[email protected]",
    username : "Test",
  },
  'vXf4WcRGQcxxxxxxxxxxxxxxxxxxx' : {
    "courseID" : "JRNGETNXXOLTUV",
    "email" : "[email protected]",
    "username" : "Test Test"
  }
};

// simulating a call to an API or DB to fetch a user
const fetchUser = (id) => {
  const user = users[id];

  return new Promise(resolve => resolve(user));
};

const fetchCourse = (courseID) => {
  // courses.find will return the first item it finds given the matching function
  const course = courses.find(course => {
    // go through all courses and return the one with a matching courseID
    return course.courseData[0].courseID === courseID;
  });

  return new Promise(resolve => resolve(course));
}

const run = async () => {
  // lets wait until we get the user
  const user = await fetchUser('kwvjUSgZKXXfxxxxxxxxxxxxxxxxxx');

  // then get the courseID (assuming one to one relationship)
  const courseID = user.courseID;

  // then with that, get the one course we want from all the courses
  const course = await fetchCourse(courseID);

  // now we have the user and the course
  console.log(user, course);
};

run();