Exams - Students, Courses, Grades, Visits

/* You are given a list of students score given as text table with the following columns:
 student name, course, grade, number of visits. A student can have several grades and visits
 for the same course. Write a JavaScript function to aggregate the results and print then as JSON string.
 The input is passed as array of strings holding the table lines. Print at the console a JSON string
 that holds the courses (in alphabetical order), the average grade and average visits for each course
 and a list of students for each course (in alphabetical order). Duplicates should be removed
 (all strings are case-sensitive). Please follow exactly the JSON format from the example below.
 The average numbers should be rounded to 2 digits after the decimal point and printed without
 trailing zeroes. */

"use strict";

function aggregateStudentsResults(arr) {
        var dataMap = {};

    for (var i = 0; i < args.length; i += 1) {
        var studentData, student, course, grade, visits;
        studentData = args[i].split(/\|/).filter(Boolean);
        student = studentData[0].trim();
        course = studentData[1].trim();
        grade = parseFloat(studentData[2]);
        visits = parseFloat(studentData[3]);

        if (!(dataMap.hasOwnProperty(course))) {
            dataMap[course] = { 'avgGrade': [], 'avgVisits': [], 'students': [] };
        }

        dataMap[course].avgGrade.push(grade);
        dataMap[course].avgVisits.push(visits);
        if (dataMap[course].students.indexOf(student) < 0) {
            dataMap[course].students.push(student);
        }
    }

    function getAverageNumber(arr) {
        var sum = 0;
            arr.forEach(function (num) {
            sum += num;
            });

        return Number((sum / arr.length).toFixed(2));
    }

    function sortingObject(object) {
        var sortedKeys = Object.keys(object).sort();
        var newOject = {};
        for (var i = 0; i < sortedKeys.length; i += 1) {
            if (object.hasOwnProperty(sortedKeys[i])) {
                newOject[sortedKeys[i]] = {};
                newOject[sortedKeys[i]].avgGrade = getAverageNumber(object[sortedKeys[i]].avgGrade);
                newOject[sortedKeys[i]].avgVisits = getAverageNumber(object[sortedKeys[i]].avgVisits);
                newOject[sortedKeys[i]].students = object[sortedKeys[i]].students.sort();
            }
        }

        return newOject;
    }

    dataMap = sortingObject(dataMap);
    console.log(JSON.stringify(dataMap));
}

aggregateStudentsResults([
    'Peter Nikolov | PHP  | 5.50 | 8',
    'Maria Ivanova | Java | 5.83 | 7',
    'Ivan Petrov   | PHP  | 3.00 | 2',
    'Ivan Petrov   | C#   | 3.00 | 2',
    'Peter Nikolov | C#   | 5.50 | 8',
    'Maria Ivanova | C#   | 5.83 | 7',
    'Ivan Petrov   | C#   | 4.12 | 5',
    'Ivan Petrov   | PHP  | 3.10 | 2',
    'Peter Nikolov | Java | 6.00 | 9'
]);