Vfrdtyky

I have a semester list dropdown that when changed (i.e. onChange) should call the following function that updates the list of semesters with respect to the newly selected semester:

function updatesemesterlist() {

    var semesterlist = document.getElementById("semesterdropdown")

    var updatedsemester = semesterlist.value



    while(semesterlist.firstChild) {

        semesterlist.removeChild(semesterlist.firstChild)

    }



    semesterparts = updatedsemester.split(" ")

    var season = semesterparts[0]

    var year = semesterparts[1]



    if (season == "Fall") {

        var ny = parseInt(year, 10)

        ny += 1

        nextyear = ny.toString()



        var py = parseInt(year, 10)

        py -= 1

        prevyear = py.toString()



        addnewoption(semesterlist, "Fall" + " " + nextyear)

        addnewoption(semesterlist, "Spring" + " " + nextyear)

        addnewoption(semesterlist, updatedsemester)

        addnewoption(semesterlist, "Spring" + " " + year)

        addnewoption(semesterlist, "Fall" + " " + prevyear)

    }

    else {

        var ny = parseInt(year, 10)

        ny += 1

        nextyear = ny.toString()



        var py = parseInt(year, 10)

        py -= 1

        prevyear = py.toString()



        addnewoption(semesterlist, "Spring" + " " + nextyear) 

        addnewoption(semesterlist, "Fall" + " " + year)

        addnewoption(semesterlist, updatedsemester)

        addnewoption(semesterlist, "Fall" + " " + prevyear)

        addnewoption(semesterlist, "Spring" + " " + prevyear)

    }



    semesterlist.value = updatedsemester

    retrieveclasses(updatedsemester)

}

The function above the calls the retrieveclasses(semester) function, which updates the list of options selected based on data stored in a map structure:

function retrieveclasses(semester) {

    classes = semestertoclasses.get(semester)



    var table_body = document.getElementById("table of classes").children[1]

    while(table_body.firstChild){

        table_body.removeChild(table_body.firstChild)

    }



    console.log(classes)

    if(classes != undefined ){

        var count = 1

        for(var key of Array.from(classes.keys())){

            addclass()

            var course = document.getElementById("course-select" + (count.toString()))

            course.value = key

            course.options[course.options.selectedIndex].selected = true

            var requirement = document.getElementById("requirement-select" + (count.toString()))

            requirement.value = classes.get(key)

            requirement.options[requirement.options.selectedIndex].selected = true

            count++

        }

    }



}

For reference, the map is updated with the following function:

function saveclasses(){

    var table_body = document.getElementById("table of classes").children[1]

    var num_classes = table_body.childElementCount

    var semester = document.getElementById("semesterdropdown").value



    var courses = table_body.children



    var classtorequirement = new Map();



    for (var i = 0; i < courses.length; i++){

        var data = courses[i].children

        classtorequirement.set(data[0].firstChild.children[3].innerHTML, 

                                data[1].firstChild.children[3].innerHTML)

    }



    semestertoclasses.set(semester, classtorequirement)



}

Where semestertoclasses is initially defined at the top of my javascript file:

var semestertoclasses = new Map();

Now suppose I update the classes I want to take in the 'Fall 2018' semester and then save those courses with the 'Save Courses' button:
Fall 2018 Courses

Then I go to a new semester:
Spring 2019

When I go back to 'Fall 2018', the courses should be updated with the ones that I initially saved (CS 2800 and MATH 2940, as well as the corresponding requirements they fulfill). However, this is not the case:
After going back to Fall 2018

I debugged this issue by ensuring that the selected indices were correct (i.e. by logging options.selectedIndex to the console), and it was indeed correct. But the classes are not updated.

I'm having a hard time exactly figuring out what could cause this issue to occur. I appreciate any suggestions, thank you!