@finwo/observer

Get triggered on deep updates, without dependencies

When nested objects are accessed, a new obeserver is returned for the nested object, instead of the object itself. This allows deep path observations in complex objects.

Nothing is mapped, objects are wrapped on-demand, making sure the original object is not polluted with proxies.

Usage

import { observer } from '@finwo/observer'; // observer has a named export
import observer from '@finwo/observer';     // and is the default export as well

// Create an example object and observe it
const org   = {subject:'world',greeting:'hello',meta:{type:'test'}};
const meta  = org.meta;
const state = JSON.stringify(org);
const obs   = observer(org, (...chain) => {
  // This handler is called AFTER the target has been modified

  // Show update in console
  console.log('Update:');
  console.log('  Path:', chain.map(node => node.prop).join('.'));
  console.log('  Old :', chain[chain.length - 1].oldValue);
  console.log('  New :', chain[chain.length - 1].value);

  // Update the state
  state = JSON.stringify(org);
});

// The original object is not modified at this point
console.log(org.meta === meta); // true

// Update values
obs.subject = 'universe'; // Shows update

License

Copyright © 2022 finwo

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.