Use JSON, if it exists, otherwise fallback to Jason

[joshk]

I'm unsure if this is the best approach, so consider this more of a draft than a complete solution.

The intent is to use the JSON module from Elixir 1.18.x instead of Jason, but I've kept the Jason dep as the fallback.

I do think it would be better to have Jason as an optional dep and have the project which is using Esbuild include Jason instead, but this would also require changes when creating new Phoenix projects to make sure Jason is added in the deps.

[josevalim]

Hi @joshk!! We definitely want to do this but, because we cannot require v1.18 (it is too new), we need to depend on Jason anyway, so there isn't much benefit. My suggestion is to simply replace Jason by JSON in the future, but we will probably have to wait two years for doing so.

Other than that, I hope you are doing well and happy holidays!

[Eiji7]

@josevalim I understand we can't require using latest Elixir version, but we can optionally support it, right? The jason dependency should be optional and after said 2 years completely removed. If all libraries would do so then we can use JSON in projects that are working in latest Elixir or did I missed something?

[josevalim]

Optional dependencies are not installed by default, which means that if we make Jason optional, all projects that depend on esbuild today but do not also explicitly depend on jason, will break unless there are on v1.18. The only way we can do this transition without breaking changes is by making Elixir v1.18 a requirement.