handoff.js lets you do request/response with PubSub, using Promises.
let handoff = require('handoff');
handoff.subscribe('something', (n, message) => {
return new Promise((resolve, reject) => setTimeout(() => resolve('received!'), 1000));
});
handoff.publish('something', 'hello!')
.then(response => console.log(response)); // 'received!'publish() returns a Promise which will be resolved at the end of a subscriber chain. Subscibers can return values or promises.
nameString (required)callbackFunction (required)priorityNumber (optional)
callback will receive 1 + N arguments. The first arg will be a Notification instance, the rest will be passed in exactly in the order the publisher published them in.
priority can be useful if you have multiple subscribers, the lower the priority the sooner in the chain a subscriber will receive the notification.
nameString (required)...data* (optional)
...data (any args passed in after name) will be passed to all subscribers in order.
Each time a subsciber's listener is invoked it receives a Notification instance as the first argument. You can think of this much like an Event object.
Notifications have a name property you can use to get the name of the notification that was sent; this is useful if you have a single callback for multiple subscribers.
Notifications also have a cancel() method. This is much like stopPropagation() for events. When you call cancel() any subscribers later in the chain will not hear about that notification, and the publishers Promise will be resolved or rejected by the current subscriber.
handoff.subscribe('something', (n, message) => {
n.cancel(); // No other subscribers will hear about this notification.
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('received!'); // Publisher's `then()` method will be invoked now.
}, 1000);
});
});Handoff will reject a promise in two instances :
-
A subscriber cancelled the Notification. In these cases the Error object passed to the rejection handler will have a
codeproperty with a value ofECANCELED. -
There are no subscribers for a notification. In these cases the Error object passed to the rejection handler will have a
codeproperty with a value ofENOSYS.
This software is released under the terms of the MIT License.
(c) 2016 Taka Kojima (the "Author").
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