structuredClone

[BasixKOR]

Fixes #969

This is my naive approach to implement the structured cloning algorithm. It doesn't actually serialize and deserialize as the specification suggests, but it will give the closest clone I can replicate.

Clones

• Primitives
• Primitive wrappers
• Date
• RegExp
• Blob (Web, Deno)
• File (Web, Deno)
• FileList (Web)
• ArrayBuffer
• SharedArrayBuffer*
• DataView
• TypedArray
• ImageBitmap (Web)
• ImageData (Web)
• Array
• Object
• Map
• Set
• Error
• DOMException
• Geometry types
• WebAssembly.Module
• CryptoKey
• AudioData
• VideoFrame
• GPUCompilationMessage
• GPUCompilationInfo
• RTCCertificate

• *will not share the same memory space

NB: https://gist.github.com/petamoriken/3802602b8e93d89e5b4c21e36683cadb#gistcomment-3899514

Concerns

• Could we get rid of WeakMap dependency?
• Should structuredClone polyfill ES6 Map and Set for the environments that don't have them?
• All of instanceof calls should've been internal slot checks.
• Error.prototype.stack wildly varies between JS engines, and probably we should clone them too. Some notes can be found here.
• Blob, File and other web APIs are platform objects and their cloning behavior is defined by their IDL? Not very sure we should include this as well.

[BasixKOR]

There is a nice test suite for this algorithm in web-platform-tests, but I'm unsure the license is compatible.

[zloirock]

Could we get rid of WeakMap dependency?

Yes, I wrote above how to do it.

Should structuredClone polyfill ES6 Map and Set for the environments that don't have them?

The same as with WeakMap.

All of instanceof calls should've been internal slot checks.

It's possible to use .prototype.valuOf to check it in most cases. See below.

[zloirock]

There is a nice test suite for this algorithm in web-platform-tests, but I'm unsure the license is compatible.

You could copy those tests and add a copyright note to those tests files.

[zloirock]

All of instanceof calls should've been internal slot checks.

I think that for this case internals/classof is enough. Like:

switch (classof(value)) {
  case 'Boolean': ...
  case 'BigInt': ...
  case 'Number': ...
  case 'String': ...
  case 'Date': ...
  case 'RegExp': ...
  case 'Map': ...
}

[zloirock]

Published.