Too Long; Didn't Read
When building realtime applications, we often want to know the actual time when a process or event occurs. For example, in an instant messaging application we want to know if and when our message was delivered to the intended client. We see this in WhatsApp where messages are sent in realtime and you see status of each message when it is delivered and read, with double grey tick when delivered and double blue tick when read. We can easily build a message delivery status using Pusher and JavaScript.