如何保持所有JS一起为我的所有通知

Here I read about many types of notification system like push, web socket, nodejs etc. But those all so complex for me. So as a easy way (In my preliminary step) I am going to use Below method to make a notification(new friend, new like, new comment/reply, new mail etc). So I used particular JS and php for a particular notification.

Now I want to implement keep all together in a JS to minimize my scripts. Here I faced a problem that is every notification have different sent data and php page and different result div. So how to keep them together?

A additional Question please(I knew stackoverflow rules): Can it make my server too many connection problem?

new mail notification JS:

function addrep(type, msg){
    // do here with result
}

var name = '<?php echo $username; ?>';
function waitForMail(){
    $.ajax({
        type: "GET",
        url: "/server/mail.php",
        cache: false,
        data: {name : name
    },
        timeout:15000, 
        success: function(data){ 
            addrep("postreply", data);
            setTimeout(waitForMail, 15000 );
        },
        error: function(XMLHttpRequest, textStatus, errorThrown){
            setTimeout(waitForMail, 15000); 
        }
    });
}

$(document).ready(function(){
    waitForMail();
});

new post notification JS:

function addpost(type, msg){
    // do here with result
}

var name = '<?php echo $username; ?>';
var profileid = '<?php echo $profileid; ?>';
function waitForPost(){
    $.ajax({
        type: "GET",
        url: "/server/post.php",
        cache: false,
        data: {name : name, profileid : profileid
    },
        timeout:15000, 
        success: function(data){ 
            addpost("postreply", data);
            setTimeout(waitForPost, 15000 );
        },
        error: function(XMLHttpRequest, textStatus, errorThrown){
            setTimeout(waitForPost, 15000); 
        }
    });
}

$(document).ready(function(){
    waitForPost();
});

And all php file like as

while (true) {
    if($_GET['username']){
    $res = mysqli_query(// here) or die(mysqli_error($dbh));

    $rows =  mysqli_fetch_assoc($res);
    $id = $rows['id'];
    //etc all
    //do something
    $data['id'] = $id;
        if (!empty($data)) {
        echo json_encode($data);
        flush();
        exit(0);
        }
    }
sleep(5);
}
mysqli_close($dbh);

Well, I am not sure is this comfortable with your application design. Anyway it seems obvious that if you have to fetch notifications with the same interval it is better to have one ajax that checks everything. Something like:

$.ajax({
    type: "GET",
    url: "/server/notification.php",
    cache: false,
    data: {name : name, profileid : profileid
},
    timeout:15000, 
    success: function(data) {
        /**
        * backend should return now single object for all notification types
        * something like 
        * {
        *     newpost: { ... },
        *     mail: { ... },
        *     somethingelse: { ... }
        * }
        */
    },
    error: function(XMLHttpRequest, textStatus, errorThrown){
        setTimeout(waitForPost, 15000); 
    }
});

If you can not do it for some reasons you can keep all urls and their callbacks in object and create ajax requests in array. Something like:

// list of ajax request names and their callbacks
var reqs = {
     mail: function(data) { doSomethingWith(data);},
     post: function(data) { doSomethingWith(data);}
};

// this function will send ajax by given type
function fetchNotification(type, callback) {
    $.ajax({
        type: "GET",
        // ajax url, for example /server/mail.php
        url: "/server/" + type + ".php",
        cache: false,
        data: {name : name, profileid : profileid},
        timeout: 15000,
        success: function(data) {
            // run callback. In this example execute doSoemthingWithData
            callback(data);
            // in 15 seconds repeat this reqest
            setTimeout(function() {
                 fetchNotification(type, callback);
            }, 15000)
        },
        error: function(req, status, err){
            // something went wrong, try again in 15 seconds
            setTimeout(function() {
                fetchNotification(type, callback);
            }, 15000); 
        }
    }
}

for (var i in reqs) {
    // init first ajax for each type and its callback from reqs object
    fetchNotification(i, reqs[i]);
}