First create a view that will receive the information from your JavaScript:

# views.py

from django.http import JsonResponse

def check_requisite(request, dis_id):
    # NOTE: I changed the class name from requisite to Requisite
    # class names should be capitalized
    requisite = Requisite.objects.filter(requisite__discipline__id=dis_id)
    if requisite:
        return JsonResponse({'answer': 'It IS in the database'})
    else:
        return JsonResponse({'answer': 'NOT in the database'})

Next, add a path to that view:

# urls.py

urlpatterns = [
    ...
    path('check_requisite/<int:dis_id>', views.check_requisite, name='check_requisite'),
    ...
]

Then, in your js file, or your you send the AJAX request:

async function check_requisite(e) {
    const check = await fetch('/check_requisite/' + e.target.value);
    const answer = await check.json();
    return answer;
}

Your checkRequisite function could call the async function above, and process the answer however you wish. Of course, the answer I'm sending in the view is just a string, but it could be more data.
The answer is incomplete, but if I had more of your code, perhaps I could come up with something more complete and specific, but I think the general idea works.