This document outlines our focused tasks for TypeScript 3.8, as well as some of the discussion that explains how/why we prioritized certain work items. Nothing is set in stone, but we will strive to complete them in a reasonable timeframe.

Dates

Work Items

Expected Work Items

• Compiler Features
  • New export * as ns Syntax
  • Top-Level Await
  • Private Fields
  • Public Fields Breaking Change
  • lib.d.ts Updates
  • Better Display for Aliased Types
  • createElement Updates for React
  • Bug Squashing!
• Performance
  • Investigate Async File Reading/Writing
  • Plugin Investigation
  • Cache Type Node Construction
  • updateGraph details in TSServer responses
• Command Line Tooling
  • downlevel-dts
• Editor Productivity
  • Investigate performance improvements
    • Cross-file Go-To-Definition Fixes
    • Investigate requesting refactorings less often
  • Migration tooling investigation: Elicit feedback on...
    • Editor-Triggered .ts to .js Refactorings
    • Editor-Triggered Suggestions on Introducing a .ts File
  • Refactorings
    • Convert to Template String.
    • Extract to Constant Should Come Before Extract to Function.
    • General Discoverability
  • Quick Fixes
    • Add declare Modifier to Class Property
  • Call Hierarchy API
• Infrastructure
  • JIT deoptimization analysis
    • Find common deopts and fix them
  • Performance Diffs on PRs
  • GitHub Package Registry Publishing for @types.
  • Pull Request Debt
  • TSServer Crash Dump Infrastructure
• Documentation
  • Handbook
  • Website
  • Clarify Contributing Guidelines

Deferred Work Items

• Interactive diagnostics

Planning Meeting Notes

Motivations

• Bug backlog
• Goals and current 6-month roadmap
• GitHub user feedback (👍s)
• Feedback from customer interviews, social media, past iteration plans
• Visual Studio and Visual Studio Code feedback, as well as new functionality demands
• Actionable PRs (need to make a call)

Notes

• Compiler Features
  • New Export Forms
  • Top-Level Await
  • Private Fields (Flagged?)
  • Address anticipated feedback from 3.7
  • Lib Updates?
  • Declaration emit
    • UX
    • Performance
  • Bug Squashing!
    • Debt reduction for addressing bugs
    • Awareness of release
• Performance
  • Investigate async file-writing
  • Plugin Investigation: async plugins?
  • Declaration emit
  • updateGraph details in TSServer responses
    • Provides easier analysis for TSServer performance problems.
    • Requires synchronization with editor teams.
  • Investigate recompilation speed
    • tsc --watch isn't as fast as gulp-tsb (because it's less accurate). Is there a fast and loose mode?
• Tooling
  • dts-downlevel
    • Several library authors have explained that it is hard to support older versions of TypeScript while using the latest.
    • .d.ts files keep artifacts of your version of TS even when "uninteresting" for older versions of TS.
    • Goes back to long-standing request (e.g. readonly properties broke earlier versions of TS)
    • Enabled by typesVersions
  • Editor Productivity
    • Interactive diagnostics ❌
      • Probably won't be able to prioritize during this release.
    • Investigate performance improvements
      • Cross-file go-to-definition
        • Noticed in partner team codebases
      • Request refactorings less often
    • Investigate automatic editor migrations
      • Do existing tools solve the problem?
      • Can we do a good job in the editor?
        • CD & App building
    • Leave room open to refactoring discoverability and triggers.
      • Refactorings without spans might need to be triggerable.
    • Refactorings
      • Extract to constant should come first.
      • Refactoring for convert to template string.
• Infrastructure
  • Triage & Scheduling
  • Weekly Status Mails for Bug Reduction
  • JIT deoptimization analysis
    • VS Code extension
    • CI integration (e.g. @typescript-bot what deoptimizes?)
      • Will be learning here from general perf investigations. Not certain if this will be useful.
  • extendedDiagnostics diffs on PRs
  • GitHub Package Registry publishing for @types.
  • Expand version list for crash dumps
    • We should be looking at beta and RC.
• Documentation
  • Handbook
  • Website
  • Contributing Guidelines