observify
v2.0.0
Published
A simple function to create an observable object.
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observify
A simple function to create an observable object. You can implement observers, pub-subs, reducers and many other patterns with ease.
The function takes a target and return a proxy object, which you can subscribe to. On mutation including creation, deletion or change of any of its property, it will notify all the subscribers.
subscribers
The observable maintains a list of subscriber functions. It calls all the subscriber functions synchronously on any change to the target object. You can use ._subscribe()
and ._unsubscribe()
functions to add or remove subscribers to an observable respectively.
import { observify } from 'observify';
const target = {
loading: true,
};
const logger = state => {
console.log('updated state: ', state);
};
/* you can pass an array of subcribers as a second
* argument to add them at initialization.
*/
const observable = observify(target, [logger]);
const updateUI = (state) => {
if(!state.loading){
console.log('loading is set false');
}
};
/* you can use the ._subscribe() to add
* subscribers to your observable.
observable._subscribe(updateUI);
observable.loading = false;
/* output:
* updated state: { loading: false }
* loading is set false
*/
observable.loading = false;
/* no output, as on change the proxy does a deep
* equality check before notifying subscriber.
*/
/* you can use ._unsubscribe() to remove a
* subscriber from the observable.
observable._unsubscribe(udpateUI);
observable.loading = true;
/* output:
* updated state: { loading: true }
*/
dependency
An observable can be dependent on other observable. Which means if B is a dependency of A, A will notify all its subscribers if there is any change to B. You can use ._addDependency()
and ._removeDependency()
functions to add or remove dependency to an observable respectively.
Dependencies can be used to implement reducers. Check the example here.
import { observify } from 'observify';
const logger = state => {
console.log('updated state: ', state;
};
const observableA = observify({
foo: false,
}, [logger]);
const observableB = observify({
bar: true,
}, [logger]);
observableA._addDependency(observableB);
observableB.bar = false;
/* output:
* udpated state: { bar: false }
* updated state: { foo: false }
*/
todo
- [ ] Add option to configure deep, shallow or no check before notifying the subscribers.
- [ ] Add option to freeze the proxy object.
- [ ] Add option to call subscribers async.