Intermediate React, v6: React Server Components, Hooks & Performance vs CSS for JavaScript Developers

v6 is rebuilt around React 19 — render modes, React Server Components both from scratch and inside Next.js, transitions, optimistic and deferred values. Reviewers praise the "under the hood" RSC explanation. The honest caveat is that hooks, TypeScript and Redux content from older versions has been narrowed in favour of the RSC and performance focus.

Brian Holt is the single most consistently praised element across nine years of Hacker News mentions and official testimonials. Learners with one to three years of React experience still call the teaching "fun", "interactive" and clear. Official course rating sits at 4.7 stars.

Requires a Frontend Masters subscription ($39/month or $390/year). At a 6h22m runtime this single course is only worth the price if you pair it with the wider catalog or complete it inside one billing month. Less competitive against the free React docs if you want one course alone.

Unlike the project-based Complete Intro, the Intermediate course is modular — unrelated concepts taught as standalone lessons (RSCs from scratch, RSCs with Next.js, performance demos). Reviewers find the build-from-scratch RSC segment genuinely illuminating, but there is no single cohesive app to carry away as a portfolio artefact.

The RSC and performance material maps directly onto what teams are shipping with Next.js App Router in 2026. Learners specifically credit it with demystifying what Next.js is doing under the hood — transferable knowledge rather than tutorial-only skills.

The course covers all major CSS layout algorithms — flow, positioned, flexbox, grid — plus typography, animations, custom properties, and advanced polish techniques across 10 modules and 200+ lessons. Rather than cataloguing properties, Josh builds mental models for how each layout mode reasons about space, which multiple reviewers describe as "mastery level" coverage. The December 2025 update added subgrid and reading-flow content, keeping the curriculum current. The depth and pedagogical structure place it above any free alternative for developers who want to understand CSS rather than memorise it.

Josh W. Comeau is the most consistently praised CSS educator in independent developer communities. His personal blog (joshwcomeau.com) is cited as a reference-quality resource on its own, and the course extends that same standard of clarity into interactive format. Endorsements from Adam Wathan (Tailwind CSS creator), Kent C. Dodds (Epic React), and Laurie Barth (Netflix) are not marketing copy — each commenter is themselves a well-known practitioner. The Hacker News thread from October 2021 includes commenters praising his use of mental models such as "media queries as IF statements" as genuinely clarifying rather than simplified.

The course is available standalone on Josh's own platform (css-for-js.dev) with one-time pricing and lifetime access to updates, and also via a Frontend Masters subscription (~$39/month or $390/year). The standalone price has drawn criticism — one Hacker News commenter in 2021 noted paying $418 with taxes and called it "one heck of an expensive course," and another pointed out that the basic tier excludes flexbox and responsive design. For Frontend Masters subscribers who access it as part of a broader library, the value calculation tilts strongly positive. Regional purchasing power parity discounts and occasional sales (Valentine's Day, Black Friday) improve accessibility, but the sticker price remains the main objection in critical reviews.

Each of the 10 modules ends in a workshop — a larger, real-world-inspired project that applies the module's concepts. Students build responsive layouts, polished UI components from Figma mockups, custom form controls, and animated interactions. The interactive exercises and mini-games within lessons are consistently praised for building intuition rather than just testing recall. One reviewer's only complaint was being required to use Styled Components and React in workshops rather than their preferred tools — a minor friction point in an otherwise well-designed project sequence that demonstrates real production patterns.

The course is explicitly designed for developers working in React, Vue, or Angular component architectures, and the examples reflect production patterns rather than academic exercises. Multiple reviewers with years of professional experience report that the course changed how they reason about CSS in daily work — "less guesswork" and "more efficient" are the recurring phrases. Noel De Martin, a developer with 10+ years of experience, called it "the best course I've ever taken" and said it "should be mandatory for anyone working in the frontend." The coverage of CSS-in-JS, CSS variables, and component-level architecture maps directly to current React/Vue production workflows.