`resource-pool`

TBD

Performance report can be found here.

Changelog is here.

Preview

For a preview/playground you are welcome to:

CodePen - Observable.from() flavor
CodePen - new ObjectObserver() flavor

Install

Use regular npm install object-observer --save-prod to use the library from your local environment:

import { Observable } from 'node_modules/object-observer/dist/object-observer.min.js';

Alternatively, a CDN deployment available (AWS driven), so one can import it directly:

import { Observable } from 'https://libs.gullerya.com/object-observer/x.y.z/object-observer.min.js';

Note: replace the x.y.z with 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.

API

Library implements Observable API as it is defined here.

Additionally, from version 4.2.0 there is also '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.

Starting from 4.3.x 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

Security policy is described here. If/when any concern raised, please follow the process.

Examples

Objects

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 }

Arrays

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' for sort. 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.

Observation options

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

gullerya / resource-pool-js