How to do a http request call from client side(jade file) to server side function in js file in nodejs

I need to call a sever side function in my jade file. I tried so many methods but didn't work. Please anyone can help me? The method that i tried lastly was using export in server side function and calling it in jade file. Sample code is shown below.

insertToEnrolledSubjects.js

var MongoClient = require('mongodb').MongoClient
    , format = require('util').format;
    MongoClient.connect("mongodb://localhost:27017/test", function (err, db) {

    if (err) 
        throw err;
    else {
        console.log("successfully connected to the database!!!");

         //calling insert function
        insertToEnrolledSubjects(cid,e);

        //implementation of insert function

        exports.insertToEnrolledSubjects= function(courseid,enrolled) {
        db.collection('EnrolledSubjects').insert({ courseId:courseid ,NoOfEnrolledStudents:enrolled});

        console.log("Inserted!");

        //Show total no of reults in db
        db.collection('EnrolledSubjects').count(function (err, count) {
            if (err) throw err;

        console.log("Total Rows: " + count);
        });
        }


    }});

Sample.jade

html
    head
        title="Enroll For Subjects"
        link(rel='stylesheet', href='/bootstrap/css/bootstrap.min.css')
        link(rel='stylesheet', href='/bootstrap/css/bootstrap-responsive.min.css')
        script(src='https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js')
        script(src='bootstrap/js/bootstrap.min.js')
        script(src='C:/Users/Siyumi Amarasinghe/Desktop/mtit/routes/insertToEnrolledSubjects.js')
    body
        div.container
            div.content
                h2.display-4.m-b-2 Course criteria 
                table.table.table(border='2')
                    thead
                        tr
                            th Course ID
                            th Subject name
                            th Year
                            th Credits
                            th Action
                    tbody
                        - for (var i = 1; i <= 5; ++i){ 
                        tr
                                td=i

                                td="IPE"
                                td=i
                                td=5
                                td
                                        button.btn.btn-danger(type='submit',onclick='Enroll("#{i}")') Enroll
                                td
                                        button.btn.btn-danger(type='submit',onclick='Edit("#{i}")') Edit
                                td
                                        button.btn.btn-danger(type='submit',onclick='delete1("#{i}")') Delete
                        - }

        script.
            function delete1(d){
                var val = confirm("Do you want to delete this record?");
                if(val == true){
                    window.location.href= '/delete1/'+d;
                    return true;
                }
                else{
                    return false;
                }
                };

        script.
            function Enroll(d){
                var val = confirm("Do you really want to enroll for this course?"+d);
                if(val == true){

                    var dt = require('C:\Users\Siyumi Amarasinghe\Desktop\mtit\routes\insertToEnrolledSubjects.js');


                    dt.insertToEnrolledSubjects(d,1);



                    }};

But i'm getting this error.

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:357:11)
    at ServerResponse.header (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\response.js:730:10)
    at ServerResponse.send (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\response.js:170:12)
    at done (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\response.js:967:10)
    at Object.exports.renderFile (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\jade\lib\index.js:374:12)
    at View.exports.__express [as engine] (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\jade\lib\index.js:417:11)
    at View.render (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\view.js:128:8)
    at tryRender (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\application.js:640:10)
    at EventEmitter.render (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\application.js:592:3)
    at ServerResponse.render (C:\Users\Siyumi Amarasinghe\Desktop\mtit\node_modules\express\lib\response.js:971:7)

Please someone can explain me how to achieve this?.I need to call insertToEnrolledSubjects() function in "insertToEnrolledSubjects.js" file inside Enroll(d) function in sample.jade file. How can i achieve this?

Thanks in advance!!

via mad_ss