@knowledgecode/messenger
v0.5.0
Published
Req/Rep Pub/Sub library for iframes and workers
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Messenger
Messenger is a Req/Rep
Pub/Sub
library for iframes and workers.
Features
Allows messages to be exchanged between ...
- the main window and one or more iframes / workers.
- multiple iframes.
- multiple components.
Installation
via npm:
npm i @knowledgecode/messenger
Usage
import { MessengerClient, MessengerServer } from '@knowledgecode/messenger';
ES Modules:
<script type="module">
import { MessengerClient, MessengerServer } from '/path/to/esm/messenger.js';
</script>
Traditional:
<script src="/path/to/umd/messenger.js"></script>
<script>
// It is provided with the global variable name "messenger".
const { MessengerClient, MessengerServer } = self.messenger;
</script>
Simple Example
main.js
import { MessengerClient } from '/path/to/esm/messenger.js';
const messenger = new MessengerClient();
const worker = new Worker('/path/to/worker.js');
(async () => {
await messenger.connect('example', worker);
const answer = await messenger.req('add', { x: 2, y: 3 });
console.log(answer); // => 5
messenger.send('close');
messenger.disconnect();
})();
worker.js
importScripts('/path/to/umd/messenger.js');
const { MessengerServer } = self.messenger;
const messenger = new MessengerServer('example', self);
messenger.bind('add', data => {
return data.x + data.y;
});
messenger.bind('close', () => {
messenger.close();
// Close this worker.
self.close();
});
MessengerClient API
constructor()
const messenger = new MessengerClient();
connect(name, [endpoint[, options]])
- {string} name - unique name of the MessengerServer to connect to
- {Object} [endpoint] - an object that actually executes the
postMessage()
- {Object} [options] - connection options
The MessengerClient
must connect to a MessengerServer
via endpoint
before communication can begin. To identify the MessengerServer
to connect to, pass the unique name of the MessengerServer
as the first argument. The endpoint
is the object that actually executes the postMessage()
. If omitted, it is assumed that self
is set. The options
are connection options and members of this object are targetOrigin
and timeout
(msec). If the timeout
is omitted, this method will wait forever for a successful connection.
// To connect from the main window to a iframe.
const iframe = window.frames[0];
await messenger.connect('iframe', iframe, { targetOrigin: '*', timeout: 1000 })
.catch(e => console.log(e));
// To connect from the main window to a worker.
const worker = new Worker('/path/to/worker.js');
await messenger.connect('worker', worker, { timeout: 1000 })
.catch(e => console.log(e));
disconnect()
Disconnects from the server.
messenger.disconnect();
send(topic[, data])
- {string} topic - topic name
- {Object} [data] - an object to send
Sends a message (some object) to a topic. This method does not wait for any reply. A MessengerServer
can receive the message if it is bound to the same topic name in advance.
messenger.send('greeting', { hello: 'world' });
req(topic[, data[, timeout]])
- {string} topic - topic name
- {Object} [data] - an object to send
- {number} [timeout] - timeout (msec)
Sends a message (some object) to a topic. This method waits for some reply unlike send()
. If timeout
(msec) is omitted, this method waits forever for some reply.
const answer = await messenger.req('add', { x: 2, y: 3 })
console.log(answer);
await messenger.req('add', { x: 2, y: 3 }, 5000)
.catch(e => console.log(e)); // Catch timeout error.
subscribe(topic, listener)
- {string} topic - topic name
- {Function} listener - a listener to receive published messages
Subscribes to messages on a topic.
messenger.subscribe('news', data => console.log(data));
unsubscribe(topic[, listener])
Unsubscribes to messages on a topic. If listener is omitted, all listeners for the topic are cleared.
- {string} topic - topic name
- {Function} [listener] - a listener to receive published messages
const listener = data => console.log(data);
messenger.subscribe('news', listener);
messenger.unsubscribe('news', listener);
MessengerServer API
constructor(name, [endpoint])
- {string} name - unique name of the MessengerServer
- {Object} [endpoint] - an object that actually executes the
postMessage()
const messenger = new MessengerServer('server', self);
The name
is a unique name by which clients identify this MessengerServer. The endpoint
is the object that actually executes the postMessage()
. If omitted, it is assumed that self
is set.
bind(topic, listener)
- {string} topic - topic name
- {Function} listener - a listener to receive messages
Binds a listener to listen for messages on a topic. The topic names must be unique, no other listener than the first can bind on the same topic name. This method returns true
or false
as binding result.
messenger.bind('greeting', data => console.log(data));
messenger.bind('add', data => {
// Reply to client.
return data.x + data.y;
});
publish(topic, data)
- {string} topic - topic name
- {Object} data - an object to publish
Publish a message (some object) to all subscribers on a topic. This method does not wait for reply from the subscribers, and also does not fail even there are no subscribers at all.
messenger.publish('notification', 'The process completed successfully.');
close()
Closes all connections and shuts down the server.
messenger.close();
Browser support
Chrome, Safari, Firefox, Edge
License
MIT