object-observer provides a deep observation of a changes performed on an object/array graph.
Main aspects and features:
- implemented via native Proxy (revokable)
- observation is 'deep', yielding changes from a sub-graphs too
- nested objects of the observable graph are observables too
- changes delivered in a synchronous way by default, asynchronous delivery is optionally available as per
Observableconfiguration; more details here - observed path may optionally be filtered as per
observerconfiguration; more details here - original objects are cloned while turned into
Observables- circular references are nullified in the clone
- array specifics:
- generic object-like mutations supported
- intrinsic
Arraymutation methods supported:pop,push,shift,unshift,reverse,sort,fill,splice,copyWithin - massive mutations delivered in a single callback, usually having an array of an atomic changes
- typed array specifics:
- generic object-like mutations supported
- intrinsic
TypedArraymutation methods supported:reverse,sort,fill,set,copyWithin - massive mutations delivered in a single callback, usually having an array of an atomic changes
- intrinsic mutation methods of
Map,WeakMap,Set,WeakSet(set,delete) etc are not observed (see this issue for more details) - following host objects (and their extensions) are skipped from cloning / turning into observables:
Date
Supported:
71+ |
65+ |
79+ |
12.1 |
12.0.0+
Performance report can be found here.
Changelog is here.
For a preview/playground you are welcome to:
Use regular npm install @gullerya/object-observer --save-prod to use the library from your local environment.
ES module:
import { Observable } from '@gullerya/object-observer';CJS flavor:
const { Observable } = require('@gullerya/object-observer');Huge thanks to seidelmartin providing the CJS build while greatly improving the build code overall along the way!
CDN (most suggested, when possible):
import { Observable } from 'https://libs.gullerya.com/object-observer/x.y.z/object-observer.min.js';Replace the
x.y.zwith the desired version, one of the listed in the changelog.
CDN features:
- security:
- HTTPS only
- intergrity checksums for SRI
- performance
- highly available (with many geo spread edges)
- agressive caching setup
Full details about CDN usage and example are found here.
Library implements Observable API as it is defined here.
There is also a 'DOM-like' API flavor - constructable ObjectObserver.
This API is resonating with DOM's MutationObserver, ResizeObserver etc from the syntax perspective.
Under the hood it uses the same Observable mechanics.
Read docs about this API flavor here.
object-observer is cross-instance operable.
Observables created by different instances of the library will still be detected correctly as such and handled correctly by any of the instances.
Security policy is described here. If/when any concern raised, please follow the process.
const
order = { type: 'book', pid: 102, ammount: 5, remark: 'remove me' },
observableOrder = Observable.from(order);
Observable.observe(observableOrder, changes => {
changes.forEach(change => {
console.log(change);
});
});
observableOrder.ammount = 7;
// { type: 'update', path: ['ammount'], value: 7, oldValue: 5, object: observableOrder }
observableOrder.address = {
street: 'Str 75',
apt: 29
};
// { type: "insert", path: ['address'], value: { ... }, object: observableOrder }
observableOrder.address.apt = 30;
// { type: "update", path: ['address','apt'], value: 30, oldValue: 29, object: observableOrder.address }
delete observableOrder.remark;
// { type: "delete", path: ['remark'], oldValue: 'remove me', object: observableOrder }
Object.assign(observableOrder, { amount: 1, remark: 'less is more' }, { async: true });
// - by default the changes below would be delivered in a separate callback
// - due to async use, they are delivered as a batch in a single callback
// { type: 'update', path: ['ammount'], value: 1, oldValue: 7, object: observableOrder }
// { type: 'insert', path: ['remark'], value: 'less is more', object: observableOrder }let a = [ 1, 2, 3, 4, 5 ],
observableA = Observable.from(a);
Observable.observe(observableA, changes => {
changes.forEach(change => {
console.log(change);
});
});
// observableA = [ 1, 2, 3, 4, 5 ]
observableA.pop();
// { type: 'delete', path: [4], value: undefined, oldValue: 5, object: observableA }
// now observableA = [ 1, 2, 3, 4 ]
// following operation will cause a single callback to the observer with an array of 2 changes in it)
observableA.push('a', 'b');
// { type: 'insert', path: [4], value: 'a', oldValue: undefined, object: observableA }
// { type: 'insert', path: [5], value: 'b', oldValue: undefined, object: observableA }
// now observableA = [1, 2, 3, 4, 'a', 'b']
observableA.shift();
// { type: 'delete', path: [0] value: undefined, oldValue: 1, object: observableA }
// now observableA = [ 2, 3, 4, 'a', 'b' ]
// following operation will cause a single callback to the observer with an array of 2 changes in it)
observableA.unshift('x', 'y');
// { type: 'insert', path: [0], value: 'x', oldValue: undefined, object: observableA }
// { type: 'insert', path: [1], value: 'y', oldValue: undefined, object: observableA }
// now observableA = [ 2, 3, 4, 'a', 'b' ]
observableA.reverse();
// { type: 'reverse', path: [], object: observableA } (see below and exampe of this event for nested array)
// now observableA = [ 'b', 'a', 4, 3, 2 ]
observableA.sort();
// { type: 'shuffle', path: [], object: observableA } (see below and exampe of this event for nested array)
// observableA = [ 2, 3, 4, 'a', 'b' ]
observableA.fill(0, 0, 1);
// { type: 'update', path: [0], value: 0, oldValue: 2, object: observableA }
// observableA = [ 0, 3, 4, 'a', 'b' ]
// the following operation will cause a single callback to the observer with an array of 2 changes in it)
observableA.splice(0, 1, 'x', 'y');
// { type: 'update', path: [0], value: 'x', oldValue: 0, object: observableA }
// { type: 'insert', path: [1], value: 'y', oldValue: undefined, object: observableA }
let customer = { orders: [ ... ] },
oCustomer = Observable.from(customer);
// sorting the orders array, pay attention to the path in the event
oCustomer.orders.sort();
// { type: 'shuffle', path: ['orders'], object: oCustomer.orders }
oCustomer.orders.reverse();
// { type: 'reverse', path: ['orders'], object: oCustomer.orders }Arrays notes: Some of array operations are effectively moving/reindexing the whole array (shift, unshift, splice, reverse, sort). In cases of massive changes touching presumably the whole array I took a pessimistic approach with a special non-detailed events: 'reverse' for
reverse, 'shuffle' forsort. The rest of these methods I'm handling in an optimistic way delivering the changes that are directly related to the method invocation, while leaving out the implicit outcomes like reindexing of the rest of the Array.
object-observer allows to filter the events delivered to each callback/listener by an optional configuration object passed to the observe API.
In the examples below assume that
callback = changes => {...}.
let user = {
firstName: 'Aya',
lastName: 'Guller',
address: {
city: 'of mountaineers',
street: 'of the top ridges',
block: 123,
extra: {
data: {}
}
}
},
oUser = Observable.from(user);
// path
//
// going to observe ONLY the changes of 'firstName'
Observable.observe(oUser, callback, {path: 'firstName'});
// going to observe ONLY the changes of 'address.city'
Observable.observe(oUser, callback, {path: 'address.city'});
// pathsOf
//
// going to observe the changes of 'address' own properties ('city', 'block') but not else
Observable.observe(oUser, callback, {pathsOf: 'address'});
// here we'll be notified on changes of
// address.city
// address.extra
// pathsFrom
//
// going to observe the changes from 'address' and deeper
Observable.observe(oUser, callback, {pathsFrom: 'address'});
// here we'll be notified on changes of
// address
// address.city
// address.extra
// address.extra.data
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