[DO NOT MERGE] Proposed spikes for JSLB4

[hacksparrow]

As suggested by @bajtos - #1978 (comment).

[dhmlau]

Capturing my comments in here.

My thought process is:

1. Based on what we know about the JS experience, can we create a tutorial to let our users know how it can be done? It doesn't need to be the perfect DX but at least we can show them a way. Or we should do some enhancements before the tutorial?
2. If there's some enhancement needs to be done, what would be the MVP?

[raymondfeng]

@hacksparrow Why don't we use a github issue or wiki instead of PR to discuss the spike?

[hacksparrow]

@raymondfeng @bajtos suggested to create a markdown file and commit it.

[bajtos]

The spike has been already finished, this PR is no longer relevant.