When comparing 30 seconds of code vs exercism.org, the Slant community recommends exercism.org for most people. In the question“What are the best resources to learn JavaScript?” exercism.org is ranked 3rd while 30 seconds of code is ranked 4th. The most important reason people chose exercism.org is:
Rather than merely test for code correctness, Exercism uses peer review to improve general programming techniques. Users are encouraged to comment on others' solutions, and refine their own based on feedback.
Specs
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Pros
Pro Short and sweet
Main selling point of the project is that you can learn some useful techniques and tricks in 30 seconds or less.
Pro Lots of examples
Over 300 code snippets.
Pro ES6
Uses the latest stable features of ES6 to teach developers how to write modern code.
Pro Functional-style code
The project's code examples follow best practices for functional programming.
Pro Human review and feedback
Rather than merely test for code correctness, Exercism uses peer review to improve general programming techniques. Users are encouraged to comment on others' solutions, and refine their own based on feedback.
Pro Practice with production tools
Unlike many code practice websites, Exercism requires the user to develop and test entirely offline, submitting only the finished code. This promotes familiarity with essential tools and workflow, not just the bare language.
Cons
Con Not production-ready
A few of the code examples are not ready for production, but they can easily be made into production-ready methods with some tweaks. The library has a stable release as of August 2018.
Con Custom commandline client
Exercism requires using a CLI utility to fetch and submit exercises. This is inconvenient compared to web-only alternatives, and poses an additional barrier to entry for some users.