JavaScript: The Hard Parts, v2 vs The Web Developer Bootcamp 2025

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.