Node compatibility kept moving forward across core APIs
Deno landed a broad set of Node parity fixes in buffer, tty, process, readline, child_process, events, dns, sqlite, and http. Highlights include safer Buffer.concat, markAsUntransferable(), more correct child-process and signal semantics, readline behavior that matches Node off-TTY, improved keep-alive and h2c handling, and better events/dns edge-case support.
Runtime and performance work cut overhead in hot paths
Several internal refactors improved throughput and reduced memory churn: V8-to-Rust string conversion got cheaper, async N-API work now reuses the threadpool, URLPattern and WebIDL conversion paths were streamlined, glibc arenas are trimmed after module loading on Linux, and fs.cpSync, timer handling, and buffered file writes all saw efficiency improvements.
Security and correctness fixes landed in FFI and crypto
Nonblocking FFI now keeps ArrayBuffer backing stores alive until async work completes, removing a use-after-free risk. Crypto also got a constant-time AES-GCM tag check, fuller WebCrypto P-521 support, and tighter AES CBC/ECB key/IV validation.
Web, telemetry, and runtime behavior became more complete
OpenTelemetry now supports array-valued attributes, HTTP metrics can inherit span metadata like http.route, and watch mode now raises SIGINT/SIGTERM to JS handlers for graceful shutdown. deno eval also auto-detects CJS vs ESM, and macOS TTY handling now falls back when kqueue can’t serve a device.
Breaking docs change and install/audit fixes
deno doc --json switched to schema v2 with a new document structure, which is a breaking format change for consumers. On the package side, global npm installs now shim every bin entry, JSR lockfiles are supported for global installs, and deno audit now respects package.json overrides to avoid false positives.
Other misc changes
Various test, CI, and release updates; process.threadCpuUsage() implementation; util.MIMEType/MIMEParams; process.title/--title; ChildProcess[Symbol.dispose](); REPL and panic fixes; version bumps to 2.7.6 and 2.7.7.