JS Embedding: When to capture stack trace

[eholk]

The current Layer 1 proposal splits creating the exception object from throwing it. JavaScript exceptions usually have a stack trace associated with them. Should the embedding capture the stack trace at the point the exception is created, or when it is thrown?

See #33 (comment)

[erights]

For reference, https://github.com/tc39/proposal-error-stacks is the current proposal to standardize JavaScript error stacks.

[eholk]

Thanks!

From quickly skimming that, I assume the stack data is captured when you do new Error(), rather than at the point where you do throw? If so, it would make sense for Wasm to follow that behavior as well in the JS embedding.

[erights]

Hi @eholk , yes. Likewise, rethrowing has no effect on the captured stack trace.

It makes sense to me as well for wasm to follow this precedent. Thanks.

[aheejin]

Now we do both creation and throwing with a single throw instruction. We can create JS API that creates and throws wasm exceptions, but I think that is a separate JS API topic. Closing.