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Use javascript-mastery to create a focused learning plan with explanations and practice exercises on scope, closures, hoisting, and `var`/`let`/`const`, tailored to [current level] and [available study time].
Required inputs
[current level]
[available study time]
User-approved starter prompt based on a pinned source version; check current skill requirements before running. Task evidence ↗
SKILL.md
name: javascript-masterydescription: "33+ essential JavaScript concepts every developer should know, inspired by [33-js-concepts](https://github.com/leonardomso/33-js-concepts)."risk: criticalsource: communitydate_added: "2026-02-27"
🧠 JavaScript Mastery
33+ essential JavaScript concepts every developer should know, inspired by 33-js-concepts.
Detailed Guide
Read the detailed guide before executing this skill. It retains the complete procedure and reference material. Treat its safety, prerequisites, and validation requirements as mandatory. For focused work, load the relevant sections; for end-to-end work, read the guide completely.
When to Use This Skill
Use this skill when:
Explaining JavaScript concepts
Debugging tricky JS behavior
Teaching JavaScript fundamentals
Reviewing code for JS best practices
Understanding language quirks
Limitations
Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.