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What is BroadcastChannel API in JavaScript?

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Broadcast Channel API

The Broadcast Channel API allows us to have basic communicationi.e., sending messages between windows, tabs, frames, iframes, and workers of the same origin.

Steps to create a Communication channel:

  1. Create or join a Broadcast Channel
  2. Post the message
  3. Bind the message event

1. Create or join a Broadcast Channel

To create or join a Broadcast Channel, create a new Broadcast Channel object with the channel name. If the channel is not available, a new channel will be created.

// Connection to a broadcast channel
const bc = new BroadcastChannel('my_channel');

2. Post the message

To send a message to a channel, use the postMessage method of the Broadcast Channel object. The message can be any object.

let msg = {
    type : "settings_changed",
    settings : {
        mode : 'night'
    }
}
bc.postMessage(msg);

3. Bind the message event

When a message is posted, a message event is dispatched to each BroadcastChannel object connected to this channel. The way this event we can handle is event is shown below.

bc.onmessage = (event) => {
    let data = event.data;
    if(data.type === "settings_changed"){
        let settings = data.settings;
        // change settings(settings);
    }
}

4. Disconnect from channel

To disconnect from the connected Broadcast Channel call the close method.

// Disconnect the channel
bc.close();

The complete code

// Connection to a broadcast channel
const bc = new BroadcastChannel('my_channel');

// listen πŸ‘‚  for message
bc.onmessage = (event) => {
    let data = event.data;
    if(data.type === "settings_changed"){
        let settings = data.settings;
        // change settings(settings);
    }
}

// sending a message 
let msg = {
    type : "settings_changed",
    settings : {
        mode : 'night'
    }
}
bc.postMessage(msg);

// close connection 
bc.close();

For Further Reading

  1. Google developer site
  2. Mozilla Develper site

RELATED TAGS

broadcastchannel
javascript
community creator
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