Support for async / await

[Munjal A Patel]

What is your question?

Is it possible to use async/await in JS that will be compiled to wasm using Javy?

[Ángel M]

Hello @munjalpatel,

Not sure about your use case, but I could use async/await in my JS runtime based on Javy. The key methods are is_pending and execute_pending. They allow you to run any async method that it's waiting.

From the Javy / core crate, the run_bytecode_inner runs pending items. You only need to enable the experimental_event_loop feature:

javy/crates/core/src/execution.rs

Lines 11 to 20 in cdd9d66

 fn run_bytecode_inner(runtime: &Runtime, bytecode: &[u8]) -> Result<()> { 
     let context = runtime.context(); 
     context.eval_binary(bytecode)?; 
     if cfg!(feature = "experimental_event_loop") { 
         context.execute_pending()?; 
     } else if context.is_pending() { 
         bail!("Adding tasks to the event queue is not supported"); 
     } 
     Ok(()) 
 } 

If your use case is related to using Javy as a library to create your own JS runtime, you can use those methods to ensure QuickJS processes the async methods. I recently added this feature to a project I'm working on. You can find the code in this PR: vmware-labs/wasm-workers-server#143.

[Jeffrey Charles]

As mentioned in #386, the CLI does not currently support network requests or the fetch API.

As @Angelmmiguel mentions, you can use the library crates in Javy to create your own runtime that you compile to a Wasm module and build your own CLI around that module.

[Jeffrey Charles]

Closing this for now. Feel free to comment if you feel that your question has not been answered.