microsoft/typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
How typescript is put together
This is the native (Go) port of the TypeScript compiler ('tsgo'). The core compiler—scanner/parser, binder, checker, emitter—is written in Go under tsc/internal/*, exposed both as a CLI (tsc/cmd/tsc) and as an LSP-style language/API server communicating over pipes using a MsgPack-based protocol defined in tsc/internal/api/proto.go. A thin npm workspace package (packages/typescript) wraps platform-specific native binaries and exposes unstable JS APIs, and a VS Code extension (packages/vscode-typescript) launches and manages the language-server session. Go tooling under tools/ provides custom lint analyzers and code generators that emit TypeScript protocol/AST bindings from Go source.
Languages
Frameworks
Infrastructure
Major components
tsc/internal/compiler
File loading/parsing, module resolution, program construction, and JavaScript emission for the native compiler.
tsc/internal/checker
Type checking, inference, flow analysis, JSDoc/JSX support, and type-node printing for diagnostics and hovers.
tsc/internal/api
Implements the language-service server: sessions, request dispatch, callback filesystem, and the MsgPack wire protocol shared with JS clients.
tsc/cmd/tsc
CLI entrypoint wiring command-line compilation, the LSP server mode, and process-liveness/platform shims.
packages/typescript
npm distribution wrapper that resolves and spawns the platform-native tsgo binary and exposes unstable sync/async/AST JS APIs.
packages/vscode-typescript
VS Code extension managing language-server lifecycle, configuration middleware, status bar, project status, telemetry, and content-mapper contributions.
tools/customlint
Custom Go static-analysis passes (unexported API leakage, shadowing, parent-access bans, cleanup checks) run via golangci-lint.
tools/gen-proto
Generator that reflects over tsc/internal/api Go handlers to produce the TypeScript protocol type definitions.
A quieter week focused on stability fixes, CI speedups, and build tooling cleanup.
5 weeksWeek of 2026-08-24
Week of 2026-08-24latest
A quieter week focused on stability fixes, CI speedups, and build tooling cleanup.
Week of 2026-08-17
The big TypeScript 7 migration landed: the Go rewrite's repository layout was merged into the main repo alongside a wave of API additions and fixes.
Week of 2026-08-10
A very busy week of porting features to the Go compiler: editor completions, transpilation APIs, many crash fixes, and new platform targets.
Week of 2026-08-03
A small week with four targeted fixes to the language server and type system internals.
Week of 2026-07-27
A heavy performance-and-stability week: numerous stack-overflow and out-of-memory crashes fixed, plus broad watcher and parsing speedups.
The last few weeks show the TypeScript team steadily merging its experimental Go-based rewrite (TypeScript 7) into the main repository, bringing over dozens of bug fixes, editor improvements, and performance optimizations while also expanding the public API surface. Alongside that migration, the classic JavaScript codebase received targeted fixes and infrastructure work like faster CI and safer dependency updates. The overall arc is one of a large-scale platform transition paired with relentless polish on crashes, diagnostics, and tooling reliability.
Week by week
2026-08-24A quieter week focused on stability fixes, CI speedups, and build tooling cleanup.latest6 changes
Fix
Fixed binder race condition
Resolved a timing issue where parts of the compiler could read incomplete information during program analysis.
Refactor
Faster continuous integration
Split CI across more parallel jobs so test results come back sooner with less redundant work.
Refactor
Fewer memory allocations when checking project references
Reduced unnecessary memory use when the compiler verifies declaration directories in project references.
Fix
Fixed extension launching
Corrected a problem preventing the TypeScript extension from starting properly.
Chore
Pinned gzip for localization generation
Locked down the compression tool version used to generate translated files for reproducible builds.
Fix
Fixed crash on nil pointer during name checks
Prevented a panic in the Go-based compiler when checking certain names.
2026-08-17The big TypeScript 7 migration landed: the Go rewrite's repository layout was merged into the main repo alongside a wave of API additions and fixes.6 changes
Refactor
Applied the TypeScript 7 repository layout
Restructured the main repository to accommodate the Go-based next-generation compiler, including renaming the module and removing legacy submodules.
Feature
New API methods for type inspection
Added getReducedType(), TypeFormatFlags, StructuredType, and other tools so external programs can inspect types more richly.
Fix
Deduplicated repeated declarations on union/intersection properties
Cleaned up cases where the same property appeared multiple times when combining types.
Fix
Fixed crash in control-flow analysis for throwing for-in/for-of loops
The compiler no longer crashes when a loop's source expression can throw an error.
Feature
Content mappers round 2
Continued building infrastructure for mapping content between the old and new compiler implementations.
Chore
Improved CI infrastructure
Switched to a new GitHub runner pool, custom Go download URLs, and added a package feed check to catch release problems early.
2026-08-10A very busy week of porting features to the Go compiler: editor completions, transpilation APIs, many crash fixes, and new platform targets.6 changes
Feature
Completion snippets in the editor
Autocomplete suggestions can now offer fill-in templates, not just plain names.
Feature
Ported transpileModule and transpileDeclaration
Brought the ability to convert single files of TypeScript to JavaScript over to the new Go-based compiler.
Refactor
Balanced file assignment to checkers
Files are now distributed across parallel type-checkers more evenly using import relationships, speeding up large projects.
Fix
Many parser and diagnostic fixes
Corrected handling of exponentiation operators with 'as'/'satisfies', private names in type queries, regex Unicode sets, and several misleading or missing error messages.
Fix
LSP server reliability improvements
The language server now survives response serialization failures and handles malformed tsconfig files without crashing.
Feature
Android ARM64 release target
The native compiler can now be built and released for Android ARM64 devices.
2026-08-03A small week with four targeted fixes to the language server and type system internals.4 changes
Feature
Configurable workspace symbol search scope
Editors can now control whether workspace-wide symbol searches include JavaScript files and pass extra parameters.
Fix
Fixed LSP watcher panic
Prevented a crash when closing the file watcher at the same moment it was asked to watch new files.
Fix
Ordered variance computation by associated type symbol
Made type-compatibility calculations deterministic by processing related types in a consistent order.
Fix
Avoided false symlink mappings
Stopped the compiler from incorrectly treating physical dependencies as symlink duplicates.
2026-07-27A heavy performance-and-stability week: numerous stack-overflow and out-of-memory crashes fixed, plus broad watcher and parsing speedups.6 changes
Refactor
Optimized type narrowing operations
Speeded up the logic that figures out what a variable must be after equality checks and switch statements.
Fix
Fixed O(K^2) memory blowup in go-to-implementation
The editor feature that jumps to implementations no longer consumes runaway memory on large codebases.
Fix
Multiple stack-overflow crash fixes
Self-referential for-of loops and inherited JSDoc comments no longer cause the compiler to recurse until it crashes.
Refactor
Watcher performance improvements
File-watching got faster and now avoids pointless diagnostic refreshes triggered by irrelevant file events.
Fix
Fixed build mode stall on large solutions
Projects configured in build mode no longer hang when working with very large solutions.
Fix
Restored tsconfig diagnostics and suggestions
Misspelled tsconfig options get spelling suggestions again, misplaced options are reported, and missing TS5092/TS7059 errors were restored.
Dependencies and code review
Dependency advisories
Security Watch
1 vulnerable package (1 advisories) across 421 scanned dependencies.
adm-zip 0.5.18
1 advisory. Fixed in 0.6.0.
How it can be abusedAn attacker could send a specially crafted ZIP file that tricks adm-zip into reserving 4 gigabytes of memory, crashing or freezing whatever process reads it. In this repo that would matter mainly if build or packaging scripts ever unzip files from outside sources; the shipped compiler and language server are Go programs that never use this package.
- highGHSA-xcpc-8h2w-3j85adm-zip: Crafted ZIP file triggers 4GB memory allocation
Code review
No concrete code-level issues confirmed.
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