Use js_sys to enable node.js compatibility

[PhilippGackstatter]

This is motivated by us wanting to use libp2p in our Wasm bindings for web and node.js. This also follows from discussion in issue 2143 in rust-libp2p. The main idea for this comes from the instant crate.

I have tested the changes manually within our project and no problems came up. Is this something I should add automatic tests for? And if so, any hints on how to do that?

Thanks!

[PhilippGackstatter]

We had an issue with node.js where the process would repeatedly schedule_callbacks and never exit because of it. This issue is also present in the current master branch, so it is not related to the js_sys changes. If one adds a logging statement in that function and then runs a libp2p Wasm app in the browser, the console shows a never ending stream of log statements. This shouldn't happen, as the script has finshed execution, and all references to the objects should have been garbage collected.

In the browser this is not really noticeable, but it prevents node.js apps from exiting. @Thoralf-M came up with a fix, which still prolongs the actual execution, but it exits after some delay. An idea for a proper fix would be welcome, of course.

I marked the PR as ready for review, @tomaka or @mxinden - if you have time, we would appreciate it!

[mxinden]

Sorry for the delay here. I am not watching this repository.

I am not familiar enough with Rust's WASM ecosystem to give a proper review here. @tomaka (or maybe @expenses?) are the experts.

[mxinden]

Again, thanks for the work you are putting into this @PhilippGackstatter. Before we continue here, I would be curious what your input on libp2p/rust-libp2p#2143 (comment) would be.

[mxinden]

Crossreferencing related pull request here libp2p/rust-libp2p#2245

[Thoralf-M]

@mxinden the linked approach only works for browser, but not for node.js, so we can't use the same :(

[Thoralf-M]

@mxinden can we go forward with this PR or what's holding it up?

[mxinden]

@Thoralf-M libp2p/rust-libp2p#2245 removed wasm-timer from rust-libp2p. With that in mind, is this still needed?

[Thoralf-M]

We use it in our crate independent of libp2p

[mxinden]

I am sorry, but I am afraid I won't be able to help you here. I am not maintaining this library, nor do I have the capacity to do so in the future. You might want to consider switching to instant and futures-timer as well.