Trying to compare objects in different arrays in Javascript

Question

Array Structures

Hi, I'm building an app that shows students which courses they qualify for based on their grades. I have to filter courses that have the same subjects as the student's subjects and the mark must be>= value. I've attached an image of how the JSON looks like, the first 6 objects are the student's marks, the other 10 objects are the courses, each course has an array of subjects... these are the subjects we're checking.

• zer00ne: Post the JavaScript (like a function -- not just an object) code as a minimal reproducible example. The image you have posted is not very helpful.

Answer 1

For the student array, you can create a mark_lookup Map which points each Subject key to a Mark value. Then, you can use .filter() on your courses array to find all courses where .every() subject from the inner Subjects array has a mark_lookup value greater than or equal to the value for that particular subject.

See example below:

const student = [{Subject: "math", Mark: 75}, {Subject: "science", Mark: 45}, {Subject: "programming", Mark: 90}];
const courses = [{ Name: "Computer Science", Subjects: [{name: "math", value: 50}, {name: "programming", value: 60}] }, { Name: "Information Technology", Subjects: [{name: "programming", value: 50}] }, { Name: "Chemistry", Subjects: [{name: "math", value: 50}, {name: "science", value: 50}] }, { Name: "Psychology", Subjects: [{name: "english", value: 50}, {name: "science", value: 50}] }];
const getCourses = (student, courses) => {
 const mark_lookup = new Map(student.map(({Subject, Mark}) => [Subject, Mark]));
 return courses.filter(({Subjects}) => Subjects.every(
 ({name, value}) => (mark_lookup.get(name) || 0) >= value
 ));
}
console.log(getCourses(student, courses));

.as-console-wrapper { max-height: 100% !important;} /* ignore */

Answer 2

1) Create student marks object from student array. 2) Go thru course, and each course filter the subjects bases on the requirement. 3) push course with updated subjects to results if subjects are more than 0

const student = [
 { Subject: "English First Additional Language", Mark: 80 },
 { Subject: "Physical Sciences", Mark: 60 },
 { Subject: "Mathematics", Mark: 70 }
];
const courses = [
 {
 Name: "Computer Science",
 Subjects: [
 { name: "English First Additional Language", value: 50 },
 { name: "Mathematics", value: 80 }
 ]
 },
 {
 Name: "Information Technology",
 Subjects: [{ name: "Physical Sciences", value: 50 }]
 },
 {
 Name: "Chemistry",
 Subjects: [{ name: "Physical Sciences", value: 70 }]
 }
];
const marks = student.reduce((acc, { Subject, Mark }) => {
 acc[Subject] = Mark;
 return acc;
}, {});
const short_listed = courses.reduce((acc, { Name, Subjects }) => {
 const sel_subjects = Subjects.filter(({ name, value }) => marks[name] > value);
 if (sel_subjects.length > 0) {
 acc.push({
 Name,
 Subjects: sel_subjects
 });
 }
 return acc;
}, []);
console.log(short_listed);