Roadmap Overview

This roadmap is meant to give our team and users clarity over our priorities over the next 6 months. It's meant more as a set of guidelines than as a strict set of tasks we are bound to finish.

At a high-level, we're going to be focusing on the following 5 goals:

• Types on every desk, in every home, for every JS developer
• Productivity through strong tooling
• Approachability and UX
• Community engagement
• Infrastructure and engineering systems

The how is broken down into the following sections:

• Language design and innovation
• Developer productivity tools and integration
• Education and UX
• Community investment
• Internal engineering

If you've seen our last 6-month roadmap, you will notice that our goals and areas of investment haven't changed. The biggest change you might notice are specific work items and amount we'll be focusing on each area of investment. As an example, we're still committed to supporting editor scenarios, but right now we're more interested in ensuring that editor features are fast.

Language design and innovation

TypeScript and the core type system

• Enabling popular JS patterns in a type-safe way
• Increasing expressivity
• Proving relationships between types
• Stricter settings
• Implementing ECMAScript features

This is a continuous and iterative process. The goal of TypeScript's type system is to statically model patterns in JavaScript in a reasonable way while catching bugs and enforcing correctness. As more features are added to ECMAScript, and as we notice emerging patterns in the ecosystem, we have more work to do, and because the JavaScript world moves fast, so must we.

While nothing has changed here, we have noticed any change we make may break existing code or hurt performance. We do not believe this should deter us from investment in these areas, but we will have to test more than before. More on this later in the document.

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JavaScript: TypeScript beyond TypeScript

• Making the JavaScript editing experience better
• Smoothing the transition to TypeScript
• Automating the addition of JSDoc types
• Understanding more dynamic patterns

TypeScript isn't just for TypeScript anymore. Our userbase now includes the JavaScript ecosystem as a whole, whether they are

• using .js/.jsx files in editors powered by TypeScript,
• compiling purely with allowJs.
• type-checking with checkJs (also enabled by the // @ts-check comment), or
• transitioning to TypeScript

Whoever these users are, we believe TypeScript can serve them in some way.

The majority of our investment here will likely be for editor scenarios, migration to TypeScript, and targeting .d.ts file generation from .js files.

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Committee representation

• Optional chaining/coalescing
• Class fields (public and private)
• Decorators
• ES/CJS module interop
• Pipeline
• Protocols

We are involved in several different committees, including TC39 and the Node modules group. We try to provide representation as

• implementers of TypeScript, the type-checker
• implementers of JavaScript language services & tooling
• a voice for the users of both of the above

We're prioritizing forward compatibility with proposals/features that we've adopted early on, and we are also helping champion features which are highly-demanded from the community. As an example, our team is now involved in championing optional chaining and nullish coalescing. To maintain focus, we will likely only be engaged with a few proposals at a time.

We hold a policy of not implementing features unless they reach stage 3 and we have high confidence in them.

Developer productivity tools and integration

Editor productivity

• Editor responsiveness
• "Bread and butter" fixes & refactorings
• Migration tooling
• "Proactive" quick fixes (i.e. suggestions)
• Declaration file fixes and refactorings
  • Generate missing .d.ts files
  • Locally fork @types package

More details here

While editor responsiveness would typically land under speed, scalability, and stability, it is worth noting here because it has consistently come up as a problem. We've fixed many responsiveness bugs, but we still have more feedback to investigate.

"Bread and butter" quick fixes and refactorings refer to a class of code modifications and fixes that are applicable to most users, and generally improve everyone's quality of life. These fixes are also useful for teaching users about language features and patterns. Expect more of these, and feel free to suggest some in separate issues!

We've heard that migration is still a common pain-point, and we would like to invest in ways to ease migration to TypeScript and typed JavaScript. We have ideas here like automatic refactorings for when a file is renamed from `.js` to `.ts`.

Managing declaration files continues to be a problem, and we have more ideas for good workflows since we last considered this. We'll have to rethink our approaches here.

When possible, we may provide more in-editor suggestions with quick fixes, though these are nice-to-haves compared to the other features mentioned here.

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Linting

• Speed and scalability
• Editor integration for ESLint

ESLint is now a capable linter for TypeScript projects. There is room for improvement in editor scenarios, but we'll focus on core editor functionality and performance for JavaScript/TypeScript. We will monitor TypeScript integration in ESLint and assist the project when needed.

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Speed, scalability, and stability

• Project references/incremental polish and improvements
• Addressing performance issues
  • Finish ETW (Event Tracing for Windows) profiling support
  • Benchmark monitoring
  • Tracking down and fixing regressions
• Automated testing infrastructure for TSServer

More details here

Since the last roadmap, our benchmarking infrastructure is significantly better and uses more up-to-date versions of the 3rd party projects that we test against. We even have editor-style tests built into DefinitelyTyped to check whether any given test will significantly increase memory usage and keystroke delays. We're still continuing on automated testing infrastructure for TSServer to crawl external codebases to effectively fuzz-test them. ETW support is almost done, but is being wrapped up. We've also managed to address various regressions that have popped up.

In recent versions, we released the `--incremental` flag to enable faster compiles, with or without using project references. Still, when it comes to compiling and editing, our users have reported some scaling issues in performance. We're going to be reaching out to users to find the root cause of their issues, and finding patterns so that we can directly address the issues.

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Education and UX

New handbook

• Writing tailored intros for developers with different backgrounds
• Writing new core handbook
• Reference pages
• Infrastructure to replace look & feel, and subsume current publishing process
• Documentation around checkJs

More details here.

The handbook is close to done, and can be viewed here. We hope to be done with the core handbook in the coming months and to publish it to the new website around the end of the year.

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Error and type display UX

• Interactive diagnostics and quick info
• "Smarter" diagnostics
• More related error spans

More details here

We've made further improvements in UX and error messages, with help from the community, as well as [feedback from Microsoft's API teams](https://github.com//issues/30646) from user studies around Promise-based APIs using TypeScript. We'll continue to look for feedback from these sources.

We have been experimenting with editor UX changes that make it easy to explore types in quick info (editor tooltips) and error messages. We're holding these changes until we finish user studies on whether they actually help users fix issues more quickly.

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Playground and website

• Redesign
• Handbook integration
• New community pages
• Update examples on the website
• Playground
  • Nightly versions of TypeScript in the playground

We've already replaced the playground, and have been investigating as to whether we can make nightly versions available. We will also be working on a redesign, new pages around community meetups/conferences, and integrating the new handbook into the site.

Community investment

DefinitelyTyped

• Weekly DefinitelyTyped rotations
• Surrounding infrastructure
  • types-publisher
  • dt-mergebot
  • dtslint

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External contributors

• Easier contributions to the docs
• Open contributions to the playground and website
• Automated PR process on TypeScript

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Partner teams

We continue to elicit feedback from various partner teams, including library authors and organizations/individuals using TypeScript in interesting or broadly applicable ways. This gives us insight on various things we could improve. If you or your organization have any interesting feedback, we'd probably love to hear from you!

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API Consumers

• Rolling requests for API endpoints
• Investigate improving rich editing experiences
  • in enhancing plugins like IntelliCode
  • in templates

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Outreach

• Public talks
• Meetup attendance
• In-depth blog post content
• Help with TSConf coordination

We want to encourage members of our team to be involved with the community, and write and talk about things that they find interesting. This keeps us close to our users and makes the project itself more approachable.

Internal engineering

Team infrastructure

• Faster builds
• Linting on ESLint (and faster linting)

The idea here is really anything that improves

• stability
• productivity
• ease of contribution

for development on the TypeScript project and any of our satellite projects.

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Organizational guidance

• Internal guidance on TypeScript-first API designs
• Providing internal partner teams with best practices for projects
• Addressing major Microsoft-internal build regressions

Because we have the expertise, and because we are involved with the JavaScript community, we're able to provide a level of guidance across Microsoft to give users better experiences all around. Additionally, when we hear about major build regressions on large codebases, our internal teams can provide us with their source code, allowing us to create minimal repros (which is not always the case with external closed-source codebases). This work usually benefits external users in some way, whether it's because a bug fix generalizes, because we've produced better APIs, or because we've been able to extract new guidance.

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