Frontend Masters
Frontend Masters "JavaScript: The Hard Parts, v2" Review — Honest Analysis of 26 Developer Opinions
Will Sentance's "JavaScript: The Hard Parts, v2" is the course developers repeatedly recommend when someone wants to understand how JavaScript actually works rather than memorise more syntax. Across roughly 6.5 hours, Sentance uses blackboard diagrams and an audience-paced, Socratic style to build durable mental models of the call stack, closure, async, and prototypes. The main caveats: it is conceptual rather than project-based, there is no portfolio capstone, the intense repetition divides people, and v2 is a few years old. It also assumes solid JavaScript basics — it is not a beginner's first course.
Final score
from 26 analysed opinions
Published AI-researched, editor-audited
Distribution of opinions
Per-criterion scores
Goes deep on the JavaScript runtime model — thread of execution, the call stack, closure, the event loop, Promises and prototypes/classes — across roughly 6.5 hours. Reviewers consistently say it explains how JavaScript works "under the hood" rather than just syntax.
Will Sentance (Codesmith founder) is the most-praised element. Learners cite his blackboard diagrams, the "backpack" analogy for closure, and a Socratic, audience-paced delivery. The same intense, repetitive style is the one thing a minority find tiring.
Requires a $39/month Frontend Masters subscription rather than a one-time purchase — strong value if you use the wider catalog, weaker if you only want this one course. The course is included in the standard subscription.
This is a conceptual, exercise-and-whiteboard course, not a project build. There is no portfolio-worthy capstone, which some learners miss. The exercises are effective for drilling mental models but produce no artefact.
The mental models — call stack, closure, the event loop, async behaviour — directly explain bugs developers hit daily. Experienced developers report the course clarified concepts they had used for years without fully understanding.
What learners said
What people loved
5- Builds durable mental models of how JavaScript works under the hood — call stack, thread of execution, closure, the event loop×14
- Will Sentance's blackboard diagrams are so vivid that learners report still picturing them later when reasoning about code×11
- Audience-paced, Socratic delivery — Will adjusts speed and depth in real time based on the live workshop's questions×8
- Memorable analogies (closure explained as a "backpack" of variables) make abstract runtime concepts stick×7
- Frequently recommended even to experienced developers as the resource that finally clarified concepts they had used for years×6
What frustrated learners
5- Conceptual and whiteboard-driven rather than project-based — there is no portfolio capstone to build×7
- Will's intense, highly repetitive Socratic style divides learners — some find the constant restating tiring×5
- Requires a Frontend Masters subscription (~$39/month) rather than a one-time purchase×5
- Assumes solid JavaScript fundamentals — beginners can struggle without prior comfort in the language×4
- v2 dates from 2019; a newer v3 exists, so some examples and framing feel a little older×3
Real quotes from real users
“JavaScript the hard parts by Will Sentence really changed how I think about how JavaScript actually works.”
“If you want a video series that accomplishes a lot of the content in these books it's Will Sentance's Javascript: The Hard Parts.”
“I'd like to add a couple of resources that I've found useful - 1. All courses by Will Sentance on Frontend Masters 2. Eloquent JavaScript”
“It's auto-paced by the audience. The trainer will adjust speed and level according to a tight, real-time feedback loop with the audience.”
“He is an exceptional teacher... I can literally see his blackboard diagrams in my mind.”
“This course provided me with a clear mental model of how JavaScript works under the hood.”
“Some beginners may find the content challenging to grasp without a solid foundation in the language, and with over six hours of content, the course requires a significant time investment to complete fully.”
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How we evaluated this
This review synthesizes 26 opinions collected across the public web. Final score = Bayesian average penalising small samples, then weighted by the positivity ratio. No paid placements, no hidden agenda.
- 5 from Hacker News
- 8 from Blogs
- 9 from Official course platform
- 4 from Other