TypeScript 5.6 Iteration Plan

[DanielRosenwasser]

This document outlines our focused tasks for TypeScript 5.6. It minimally indicates intent to investigate tasks or contribute to an implementation. Nothing is set in stone, but we will strive to complete these tasks in a reasonable timeframe.

Date	Event
2024-06-18	TypeScript 5.5 Release
2024-07-19	Create 5.6 Beta (5.6.0) Build for Testing
2024-07-23	TypeScript 5.6 Beta Release
2024-08-16	Create 5.6 RC (5.6.1) Build for Testing
2024-08-20	TypeScript 5.6 RC Release
2024-08-30	Create 5.6 Final (5.6.2) Build for Testing
2024-09-03	TypeScript 5.6 Final Release 🚀

gantt
    dateFormat  YYYY-MM-DD
    TypeScript 5.5 Stabilization Period : 2024-06-10, 2024-06-18
    TypeScript 5.6 Beta Development : 2024-06-10, 2024-07-20
    TypeScript 5.6 RC Development : 2024-07-20, 2024-08-16
    TypeScript 5.6 Stabilization Period : 2024-08-16, 2024-09-03
todayMarker stroke-width:5px,stroke:#0f0,opacity:0.5

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Compiler and Language

• Investigate Strict Callback Analysis
• Stricter TReturn and TNext Types for next() on Iterators
• Checks for Never-Initialized Variables
• ECMAScript Arbitrary Module Identifiers
• Consult type in node_modules/**/package.json in More Module Modes
• Spelling Suggestions for Named Capture Groups
• Investigate skipCheck/noCheck in API and Batch-Mode Compilation
• Build All Projects Under --build Irrespective of Errors
• Investigate Non-Null Assertions in JSDoc
• lib.d.ts Updates

Editor and Language Service

• Investigate Expandable Quick Info/Hover Verbosity
• Region-Prioritized Error Checking
• Investigate Simpler Quick Fix API
• Investigate LSP Support
• Auto-Import on Paste
• Provide Deprecated Diagnostics on Namespaces Declared with module Keyword

Performance

• Investigate and Experiment with Full Monomorphization
• Investigate Wildcard Matching Performance
• Optimize Path Mapping Lookups
• Investigate Deferring TransformFlags Calculation

Website and Docs

• Revisit/Review Handbook and Experiences
• Simplify and Refactor Website for Faster Builds

Infrastructure

• Investigate Provenance or Build Signing
• Experiment with Reduced Repros on Weekly New Error Runs
• Adopt --isolatedDeclarations and Parallelize TypeScript's Build

[MunMunMiao]

I hope you can consider #26242 and #59126. We really hope to be able to use optional generics.

[ghiscoding]

Could this next plan be pinned instead of previous 5.5 which is now closed, it was hard to find. Thanks

[zanminkian]

I hope #59051 can be fixed in 5.6. Otherwise, many TypeORM or NestJS projects will implicitly have bugs if they use declare keyword.

[graphemecluster]

“Investigate Non-Null Assertions in JSDoc” should link to #57042 instead.
And the beta release date has supposedly passed but it has not yet been merged. I guess there’s not much to review?

^{P.S. A little thank you for listing #58613 here. It’s my pleasure.}

[DanielRosenwasser]

@typescript-bot create release-5.6

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
create release-5.6	✅ Started	✅ Results

[typescript-bot]

Hey, @DanielRosenwasser! I've created release-5.6 with version 5.6.0-beta for you.

[DanielRosenwasser]

TypeScript 5.6 Beta is available!

[Infinitay]

Thanks for all the work on the new upcoming release. If it's not too late, I would like to appeal a suggestion to add support for importing json files as const as described in #32063.

[DanielRosenwasser]

@typescript-bot sync release-5.6

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
sync release-5.6	✅ Started	✅ Results

[typescript-bot]

Hey, @DanielRosenwasser! I've pulled main into release-5.6 for you.

[DanielRosenwasser]

@typescript-bot bump release-5.6