Socket.io emit and .on not working - node.js

Question

I am learning Node js with socket. I got a sample program from Here
When I try to run it, it is not showing the error, but also nothing happening.
I tried and find out that the socket.emit and socket.io are not triggering.
Client side
$("#addComment").click(function(event){
var userName = $("#name").val();
var userComment = $("#comment").text();
if(userName === "" || userComment === "") {
alert("Please fill the form.");
return;
}
socket.emit('comment_added',{user : userName, comment : userComment});
socket.on('notify_everyone',function(msg){
notifyMe(msg.user,msg.comment);
});
});
function notifyMe(user,message) {
// Let's check if the browser supports notifications
if (!("Notification" in window)) {
alert("This browser does not support desktop notification");
}
// Let's check if the user is okay to get some notification
else if (Notification.permission === "granted") {
// If it's okay let's create a notification
var options = {
body: user + "Posted a comment" + message,
dir : "ltr"
};
var notification = new Notification("Hi there",options);
}
// Otherwise, we need to ask the user for permission
// Note, Chrome does not implement the permission static property
// So we have to check for NOT 'denied' instead of 'default'
else if (Notification.permission !== 'denied') {
Notification.requestPermission(function (permission) {
// Whatever the user answers, we make sure we store the information
if (!('permission' in Notification)) {
Notification.permission = permission;
}
// If the user is okay, let's create a notification
if (permission === "granted") {
var options = {
body: user + "Posted a comment" + message,
dir : "ltr"
};
var notification = new Notification("New comment added.",options);
}
});
}
// At last, if the user already denied any notification, and you
// want to be respectful there is no need to bother them any more.
}
Server side
io.on('connection',function(socket){
console.log('We have user connected !');
io.sockets.on('comment_added',function(data){
console.log(data);
db.addComment(data.user,data.comment,mysql,pool,function(error,result){
if (error) {
io.emit('error');
} else {
socket.broadcast.emit("notify_everyone",{user : data.user,comment : data.comment});
}
});
});
});

Answer 1

You need to put the
socket.on('notify_everyone',function(msg){
notifyMe(msg.user,msg.comment);
});
outside of the function it is currently in, or else it won't be run (that code is only run when the comment is clicked).
For example,
$("#addComment").click(function(event){
var userName = $("#name").val();
var userComment = $("#comment").text();
if(userName === "" || userComment === "") {
alert("Please fill the form.");
return;
}
socket.emit('comment_added',{user : userName, comment : userComment});
});
socket.on('notify_everyone',function(msg){
notifyMe(msg.user,msg.comment);
});
Also, there is documentation on the socket.io website as well as a chat app tutorial