Ready to implement a chat application using Twilio Programmable Chat Client, Node.js and Express?
This application allow users to exchange messages through different channels, using the Twilio Programmable Chat API. On this example, we'll show how to use this API capabilities to manage channels and their usages.
For your convenience, we consolidated the source code for this tutorial in a single GitHub repository. Feel free to clone it and tweak as required.
In order to create a Twilio Programmable Chat client, you will need an access token. This token holds information about your Twilio Account and Programmable Chat API keys.
We generate this token by creating a new
AccessToken and providing it with an
ChatGrant. The new AccessToken object is created using your Twilio credentials.
We can generate a token, now we need a way for the chat app to get it.
On our controller we expose the endpoint for token generation. This endpoint is responsible for providing a valid token when passed this parameter:
identity: identifies the user itself.
Once we have used the
tokenService object to generate a token we can use the AccessToken's method as
token.toJwt() to get the token as a String. Then we just return the token as a JSON encoded string.
Now that we have a route that generates JWT tokens on demand, let's use this route to initialize our Twilio Chat Client.
Our client fetches a new Token by making a POST request to our endpoint when it calls the
With the token we can then instantiate
Now that we've instantiated our Chat Client, lets see how we can get a list of channels.
After initializing the client we can use its
getPublicChannelDescriptors method to retrieve all visible channels. The method returns a promise which we use to show the list of channels retrieved on the UI.
Next, we need a default channel.
This application will try to join a channel called "General Channel" when it starts. If the channel doesn't exist, we'll create one with that name. The scope of this example application will show you how to work only with public channels, but the Programmable Chat client allows you to create private channels and handle invitations.
Notice we set a unique name for the general channel as we don't want to create a new general channel every time we start the application.
Now let's listen for some channel events.
Next we listen for channel events. In our case, we're setting listeners to the following events:
messageAdded: When another member sends a message to the channel you are connected to.
typingStarted: When another member is typing a message on the channel that you are connected to.
typingEnded: When another member stops typing a message on the channel that you are connected to.
memberJoined: When another member joins the channel that you are connected to.
memberLeft: When another member leaves the channel that you are connected to.
We register a different function to handle each particular event.
The client emits events as well. Let's see how we can listen to those events as well.
Just like with channels, we can register handlers for events on the Client:
channelAdded: When a channel becomes visible to the Client.
channelRemoved: When a channel is no longer visible to the Client.
tokenExpired: When the supplied token expires.
For a complete list of client events
We've actually got a real chat app going here, but let's make it more interesting with multiple channels.
When a user clicks on the "+ Channel" link we'll show an input text field where it's possible to type the name of the new channel. Creating a channel is as simple as calling
createChannel with an object that has the
friendlyName key. You can create a channel with more options listed on the Channels section of the Programmable Chat documentation.
Next, we will see how we can switch between channels.
When you tap on the name of a channel from the sidebar, that channel is set as the
selectChannel method takes care of joining to the selected channel and setting up the
At some point your users will want to delete a channel. Let's have a look at how that can be done.
Deleting a channel is easier than creating one. The application lets the user delete the channel they are currently on through the "delete current channel" link. The only thing you need to do to actually delete the channel from Twilio, is call the
delete method on the channel you are trying to delete. Like other methods on the
Channel object, it'll return a promise where you can set the success handler.
That's it! We've just implemented a simple chat application for Node.js using Express.
If you are a Node developer working with Twilio, you might want to check out these other tutorials:
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Thanks for checking out this tutorial! If you have any feedback to share with us, we'd love to hear it. Tweet @twilio to let us know what you think.