Implement JSG_TRY / JSG_CATCH macros #6021
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Add new macros for exception handling in JSG code that automatically convert
both JavaScript exceptions (JsExceptionThrown) and KJ exceptions (kj::Exception)
to jsg::Value. This enables cleaner exception handling syntax and prepares for
future coroutine support with co_await on jsg::Promise.
The implementation uses a JsgCatchScope helper class that sets up a v8::TryCatch
on construction and converts caught exceptions via catchException(). The macros
use the "goto-dead-else-branch" pattern from KJ_TRY/KJ_CATCH for clean syntax.
Usage:
JSG_TRY(js) {
someCodeThatMightThrow();
} JSG_CATCH(exception) {
return js.rejectedPromise<void>(kj::mv(exception));
}
Co-authored-by: Claude <noreply@anthropic.com>
Replace some manual v8::TryCatch usage with the new JSG_TRY/JSG_CATCH macros to try them out. Co-authored-by: Claude <noreply@anthropic.com>
jasnell
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Feb 6, 2026
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jasnell
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I know humans aren't likely to read it, but it's good for the LLMs... can you add some details about this to the jsg/README.md?
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Good idea, done. |
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Implement JSG_TRY / JSG_CATCH macros
Add new macros for exception handling in JSG code that automatically convert
both JavaScript exceptions (JsExceptionThrown) and KJ exceptions (kj::Exception)
to jsg::Value. This enables cleaner exception handling syntax and prepares for
future coroutine support with co_await on jsg::Promise.
The implementation uses a JsgCatchScope helper class that sets up a v8::TryCatch
on construction and converts caught exceptions via catchException(). The macros
use the "goto-dead-else-branch" pattern from KJ_TRY/KJ_CATCH for clean syntax.
Usage: