Add support for serializing this when invoking step functions
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🦋 Changeset detectedLatest commit: 15c9b77 The changes in this PR will be included in the next version bump. This PR includes changesets to release 15 packages
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🧪 E2E Test Results❌ Some tests failed Summary
❌ Failed Tests🌍 Community Worlds (21 failed)mongodb (1 failed):
redis (1 failed):
starter (18 failed):
turso (1 failed):
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Pull request overview
This PR adds support for serializing the this context when invoking step functions, enabling the use of JavaScript's .call() and .apply() methods with step functions.
- Modified step function creation to use a regular function instead of an arrow function to capture
thiscontext - Added optional
thisValproperty to the step invocation queue item interface - Enhanced serialization/deserialization flow to handle
thisValalongside existingargsandclosureVars
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/core/src/step.ts | Changed to regular function to capture this and conditionally serialize it when not undefined/null/globalThis |
| packages/core/src/global.ts | Added optional thisVal property to StepInvocationQueueItem interface |
| packages/core/src/runtime/suspension-handler.ts | Included thisVal in the dehydrated step input |
| packages/core/src/runtime/step-handler.ts | Hydrated and applied thisVal when executing step functions, updated comment |
| workbench/example/workflows/99_e2e.ts | Added example workflow demonstrating .call() and .apply() usage with step functions |
| packages/core/e2e/e2e.test.ts | Added e2e test validating thisSerializationWorkflow behavior |
| .changeset/old-pugs-win.md | Added changeset documenting the patch-level change |
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📊 Benchmark Results
workflow with no steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro | Express workflow with 1 step💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) | Express workflow with 10 sequential steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro | Express Promise.all with 10 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) | Express Promise.all with 25 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) | Express Promise.race with 10 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) | Express Promise.race with 25 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Express | Next.js (Turbopack) Stream Benchmarks (includes TTFB metrics)workflow with stream💻 Local Development
▲ Production (Vercel)
🔍 Observability: Express | Nitro | Next.js (Turbopack) SummaryFastest Framework by WorldWinner determined by most benchmark wins
Fastest World by FrameworkWinner determined by most benchmark wins
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Added support for serializing
thiscontext when invoking step functions.What changed?
thiscontext when it's defined and not the global objectthisValpropertythisValwhen executing step functionsWhy make this change?
This enhancement allows step functions to be invoked with an explicit context object using standard JavaScript methods like
.call()and.apply(). This is particularly useful for step functions that need to access properties from a specific context, enabling more flexible and idiomatic JavaScript patterns within workflows.