React-Mqtt-Hooks is a library that simplifies the integration of MQTT (Message Queuing Telemetry Transport) functionality into React applications. It provides a set of custom hooks that allow developers to easily connect to an MQTT broker based on the popular MQTT.js library.

With these hooks, you can publish messages to specific topics and subscribe to receive messages from the broker. The library seamlessly synchronizes the received MQTT messages with the state of your React functional components, enabling real-time updates and efficient data handling within your application.

• Global Cache: The message received from the MQTT broker is stored in a global cache, which can be accessed from any component in the application.
• Real-time Updates: The library automatically updates the state of your components when new messages are received from the broker.

npm i react-mqtt-hooks
# or
pnpm add react-mqtt-hooks

1. First, wrap your application with the MqttConnector component and provide the MQTT Broker URL and the connection options.

   import { MqttConnector } from "react-mqtt-hooks";
   
   function App() {
     return (
       <MqttConnector
         url="ws://example-broker-url/mqtt"
         options={{
           clientId: "your-client-id",
           username: "your-username",
         }}
       >
         {/* Your components */}
       </MqttConnector>
     );
   }

2. Then, use the useTopic hook to subscribe to a topic and receive messages from the broker in your components within the MqttConnector component.

   import { useTopic } from "react-mqtt-hooks";
   
   function ChatMsg() {
     // This hook return a Buffer object from Broker,
     // you can use toString() to convert it to a string
     // or whatever you want.
     const msg = useTopic("chat");
   
     return (
       <div>
         <h1>Messages from the broker:</h1>
         <p>{msg?.toString()}</p>
       </div>
     );
   }

   useTopic will cache the last message data received from the broker and update the component state under the hood. This concept is inspired by the SWR library.

   Multiple useTopic hook with same topic will share the same message data cache. This means you can call useTopic accross different components and they all will behave the same.

The MqttConnector component is a provider that wraps your application and provides the MQTT.js client instance and connection status to the context. It also handles the connection and disconnection of the client.

import { MqttConnector } from "react-mqtt-hooks";

function App() {
  return (
    <MqttConnector
      url="ws://example-broker-url/mqtt"
      options={{
        clientId: "your-client-id",
      }}
    >
      {/* Your components */}
    </MqttConnector>
  );
}

The useMqttConnector hook is used to access MqttConnector component context. It provides 2 values:

• client: The MQTT.js client instance, more details about the client instance can be found in the MQTT.js documentation.
• status: The connection status of the client.

import { useMqttConnector } from "react-mqtt-hooks";

function MyComponent() {
  const { client, status } = useMqttConnector();

  return (
    <div>
      <p>Client ID: {client?.options.clientId}</p>
      <p>Status: {status}</p>
    </div>
  );
}

The useTopic hook is used to subscribe to a specific topic and receive messages from the broker. It returns the last message buffer received from the broker. You can convert it to whatever you want.

import { useTopic } from "react-mqtt-hooks";

function MyComponent() {
  const msg = useTopic("my-topic");

  return <p>{msg?.toString()}</p>;
}