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selfAddr & selfName

selfName

window.webxdc.selfName

selfName is the nick or display name for the user which the webxdc application may show in its user interface.

selfAddr

window.webxdc.selfAddr

A string ("unique ID") identifying the user in the current webxdc application. Every user of a webxdc application must get a different selfAddr. The selfAddr must be the same if the webxdc is started again later for the same user, on the same or on a different device. The same user opening a different webxdc application, however, SHOULD have a different selfAddr to avoid linkability between apps: even if a web app manipulates users to share selfAddr values via copy+paste to another web app, addresses between the two web apps should not be linkable.

Note that selfAddr

  • has no meaning outside the webxdc application,

  • should not be shown in the user interface of the webxdc application (use selfName instead).

isAppSender

window.webxdc.isAppSender

isAppSender is a boolean value that is true if the local user is the one who initially shared the webxdc application in the chat. If it is false, the user is a receiver.

This supports a common development model where a "central" app instance (the sender's) processes all updates and distributes the resulting state back to all peers.

isBroadcast

window.webxdc.isBroadcast

isBroadcast is a boolean value that is true if the webxdc application is shared in a broadcast chat context.

On some platforms, such as "broadcast channels," it is technically impossible for subscribers to discover or send updates to each other directly. In those cases, updates sent by a non-sender will only be seen by the app sender, who alone can distribute updates globally.

Example using selfAddr and selfName

Here is a simple chat app that sends out a reply using the display names but uses the addresses for notifications.

// Receive a message from anyone in the chat
let users = new Set();

window.webxdc.setUpdateListener((update) => {
    const prompt = `${update.payload.senderName} (${update.payload.senderAddr}):`;
    users.add(update.payload.senderAddr);
    console.log(`${prompt} ${update.message}`);
});

// start some user interface which calls the following function for
// message sending

function sendMessage(text) {
    let payload = {
        senderAddr: window.webxdc.selfAddr,
        senderName: window.webxdc.selfName,
        message: text
    };

    // notify all users who ever sent a message in the chat app
    let notify = {};
    for (const addr of users) {
        notify[addr] = `new message from ${webxdc.selfName}`;
    }

    window.webxdc.sendUpdate({
        payload: payload,
        notify: notify
    });
})