JavaScript — 2026 Week 29

Following Node.js 20's upstream end-of-life on April 30, 2026, Vercel will disable Node.js 20 in Project Settings on October 1, 2026, causing new deployments of Serverless Functions pinned to Node 20 to error out — existing deployed functions continue working. Teams can identify affected projects today with vercel project ls --update-required after installing vercel@latest. The preferred upgrade path is setting "node": "24.x" in the engines field of package.json, which overrides Project Settings on the next deploy. Teams unable to migrate in time can containerize via a Dockerfile.vercel at the project root, but then own their own Node security patches going forward.

Astro 7.1 adds four focused improvements to the static-site framework released July 16, 2026. CSP gets new built-in directives that separate script-src-elem from script-src and style-src-attr from style-src, letting you allow unsafe inline styles without relaxing rules for external CSS. The paginate() helper gains a format function parameter so generated next/prev URLs match your actual deploy layout (e.g., appending .html for static hosts without URL rewriting). A new --ignore-lock flag on astro dev bypasses the agent-lockfile check introduced in Astro 7, enabling multiple intentional dev-server instances that run outside astro dev stop management. For large content collections, the new deferRender: true option on glob() skips eager HTML caching at sync time, and the experimental collectionStorage: "chunked" flag splits the .astro/data-store.json into 10 MB chunks, avoiding platform file-size limits.

ESLint and Codemod — an OpenJS Foundation partner whose engine (JSSG) powers migrations for React, Node.js, Nuxt.js, and pnpm — have partnered to automate v8→v9 and v9→v10 migrations, with all codemods living in the eslint/codemods repo and auto-published to the Codemod Registry via GitHub Actions. For v8-to-v9, npx codemod @eslint/v8-to-v9-config extracts eslintConfig from package.json, generates a flat eslint.config.mjs, and handles rule-option changes for no-unused-vars, camelcase, and six others; a companion @eslint/v8-to-v9-custom-rules migrates context method calls like context.getSource() to sourceCode.getText() and converts function-style rules to the object format with meta and create. The v9-to-v10 recipe (npx codemod @eslint/v9-to-v10) bundles four individual codemods covering config, custom rules, RuleTester, and the Linter/ESLint API. Complex logic such as dynamic require() and --ext CLI usage still requires manual review after running.

Preact contributor Jovi De Croock explains that Preact already supports resumed hydration — Suspense boundaries hydrate independently via renderToStringAsync on the server and pause-and-continue on the client — but the original algorithm tracked only one DOM node per suspended subtree, causing mismatches when a component returned null or a Fragment with multiple roots. Hydration 2.0, shipping as part of Preact 11, replaces that assumption with explicit opening and closing markers emitted by renderToStringAsync, so Preact can identify the complete DOM range for any suspended boundary before resuming it. One remaining open problem is useId() stability: a PR to fix id drift across async Suspense siblings (PR #5108) had to be reverted in #5135 because client-only branches shifted tree positions and reintroduced the same id-collision bug. Streaming SSR — where the server flushes the shell and fallback immediately on encountering a suspending child — is also in progress for Preact 11.

Author Riccardo Perra traces how TanStack Table V9 evolved from a proxy-based Angular adapter — where get* methods were wrapped in computed() calls via a Proxy — through notifier bridges and class-based Store and Derived APIs, to the current architecture where per-feature atoms (pagination, row selection, column sizing, filters) live in a reactive graph built on @tanstack/store 0.9's signal-backed createStore/createAtom API. PR #6181 moved options into an optionsStore so that live inputs like enableRowSelection participate in the same dependency graph as state reads; PR #6234 split the monolithic state snapshot into per-feature atoms; PR #6237 made those atoms framework-swappable via a TableReactivityBindings interface (createWritableAtom, createReadonlyAtom, batch, schedule, untrack). Angular, Solid, and Vue now supply native signals; React uses @tanstack/react-store with a Subscribe component and useSelector for opt-in granular rendering. V9 ships nine framework adapters, including new Preact, Alpine, and Ember adapters.