Replace dirty checking with Proxy object

[warpech]

Proxy is a ES2016 feature that can replace dirty checking in https://github.com/Starcounter-Jack/JSON-Patch/blob/master/src/json-patch-duplex.ts

I think that the correct way is to replace the current dirty checking recursively with Proxy objects. The support in old browsers should be provided with a polyfill.

First step is to make a proof of concept implementation and check if the polyfill is capable of running it.

Read more:

• Proxy (developer.mozilla.org)
• proxy-polyfill (github.com)
• Browser support (caniuse.com)
• Metaprogramming with proxies

[warpech]

There might be a problem with proxy-polyfill. Readme says:

The polyfill supports just a limited subset of proxy 'traps', and comes with a caveat: it invokes seal on any proxied object so that no additional properties can be defined.

This means that we will not be able to add traps to properties added after the initial page load.

Maybe actually we can achieve what's needed by forking proxy-polyfill.

[warpech]

Also, the performance cost of Proxy is quite significant: http://jsperf.com/es2015-proxy-test3. But I haven't yet compared it to the cost of dirty checking.

[warpech]

I know that some other frameworks attempted adapting Proxy and failed: vuejs/vue#3020. But perhaps our case is different.

[MarkHerhold]

What is 'our case'?

[warpech]

What is 'our case'?

Deep observing of a plain Javascript object without modifying it.

[alshakero]

Can I close this?

[warpech]

Yes. Patch generation using ES6 Proxy was implemented as a separate package: https://github.com/Palindrom/JSONPatcherProxy

In this repo we continue to have dirty-checking based patch generation, but it will be deprecated in future. Follow #151