Wapi.js SDK implements Node.js native EventEmitter class to implment event handling.

​
Listen to Events:

You can listen to events using the on method available on the client class. Here is an example of how you can listen to incoming messages and reply/react to them: 
// assuming you have already initiated the client,


whatsappClient.on('Ready', async () => {
        console.log("Client is ready to receive messages.")
})

whatsappClient.on('Error', async error => {
        console.errpr("An error occured.", error)
})

whatsappClient.on('TextMessage', async message => {
        await message.reply({
            message: new TextMessage({
                text: 'This is a reply.'
            })
        })
})

whatsappClient.on('AudioMessage', async message => {
        await message.reply({
            message: new TextMessage({
                text: 'This is a reply.'
            })
        })
})

// and so on for other message types...

​
Exposed Events

The SDK supports the following events out of the box to make it easy to handle both the user and system events:
There is no messaging or system event handling differences in the SDK, here they are just bifurcated for the educational puposes.

​
Messaging Events:

Important

Each of the events mentioned above has a couple of utility methods available like reply, react etc. which can be used to reply or react to the incoming messages.

​
System Events