TypeScript 4.8 Iteration Plan

[DanielRosenwasser]

This document outlines our focused tasks for TypeScript 4.8. 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
May 24th	TypeScript 4.7 Release
June 17th	Create 4.8 Beta (4.8.0) Build for Testing
June 21st	TypeScript 4.8 Beta Release
August 5th	Create 4.8 RC (4.8.1) Build for Testing
August 9th	TypeScript 4.8 RC Release
August 19th	Create 4.8 Final (4.8.2) Build for Testing
August 23th	TypeScript 4.8 Final Release 🚀

Language and Compiler Features

• ECMAScript Decorators
• Improved Inference for infer Types in Template String Types
• Investigate Contextually Typed And Compatible Operator
• Continue Investing in Type Annotations Proposal
• Investigate --isolatedDeclaration Emit Mode
• Improve Conformance for Arrow Functions in Conditional Expressions
• Investigate Narrowing Generics By Truthiness
• Investigate --watch Issues on Checkouts
• lib.d.ts Updates

Editor Productivity

• Prototype Virtual File System Support in TSServer
• Investigate Cancellation in Browser Contexts
• Prototype Automatic Type Acquisition in Web Contexts
• Provide Walkthroughs in Visual Studio Code Welcome View
• Easy Run/Debug for Loose TypeScript Files
• Investigate TS Server Plugins on the Web

Performance

• Investigate Tooling for JIT Deoptimizations
• Investigate Outstanding Performance Issues
• Enrich TS Server Tracepoint

Infrastructure

• Determining Module Migration and Shipping Strategy
• Fuzzer Improvements and Addressing Crashes
• TSServer Performance Testing Infrastructure
• Expand Perf Suite

Website

• Accessibility Improvements
• Investigate Playground as a VS Code Extension

[ghiscoding]

I wonder when will any of the opened issues related to Scenario: Monorepos & Cross-Project References will ever be worked and/or looked into? I'd be really interested to see this one in particular #30235, to build with multi-threads, and it's been open for so long without any real tractions. Are there any plans short term? When should we expect any movements in Monorepo subjects from TypeScript team? When will TypeScript ever take advantage of multi-threaded compilations? I'm sure plenty of users would enjoy the perf boost when doing a build... Anywho, I'm still happy to see plenty of features ship every couple months, keep up the good work TS Team 🚀

[JustFly1984]

Please include #17002 Array.isArray with ReadonlyArray

[Jack-Works]

please consider #49077!

[arendjr]

Please consider addressing #37582 and #49083.

[Eliav2]

#10571 (Allow skipping generics) would be highly appreciated

[DanielRosenwasser]

@ghiscoding the multithreaded build issue is something that is unfortunately hard with the synchronous foundation we have. There is also some amount of work sharing between project builds that we would likely lose. On the flip side, we did land some great optimizations between --build/--watch/--incremental in time for the beta. You can try them in our current nightlies.

[DanielRosenwasser]

@typescript-bot create release-4.8

[typescript-bot]

Heya @DanielRosenwasser, I've started to create the release-4.8 branch for you. Here's the link to my best guess at the log.

[kasperpeulen]

@DanielRosenwasser Is there any chance that the satisfies operator will land in 4.8?