We are assessing for five capacities in applicants:
Technical communication, problem solving, JavaScript and programming knowledge, nontechnical communication and engineering best practices (Read more here on Quora)
Top resources for technical communication, problem solving and best practices:
Pair-programming and going under-the-hood of JavaScript at JS the Hard Parts and Saturday workshops at Codesmith
CSX, Codesmith's free online learning courses with challenges and projects
Coding Challenge sites like Codewars, Coderbyte, Leetcode, HackerRank, Project Euler
Web development challenge sites like Nodeschool and Exercism.io
PythonTutor - Allows you to run through your code line by line similar to the JS the Hard Parts whiteboarding approach. Run each of your Codewars solutions through PythonTutor to ensure you truly understand your solution
JavaScript30 - Build a project with simple JavaScript each day for 30 days - excellent for improving your problem-solving (Tackle the problem before watching any solution)
Top resources for JavaScript and programming knowledge:
CSX - Codesmith's Free Online Courses
freeCodeCamp
Codewars (and other coding challenge sites)
JS the Hard Parts
(Thursday workshop 6:30pm at Codesmith online and in-person)
JS the Weird Parts (Udemy)
ReactiveX LearnRX challenges (Higher order functions)
Angus Croll on JavaScript (Closures, Execution Context, etc.)
More introductory resources:
Codecademy JavaScript
Codeschool JS
Team Treehouse
Eloquent JavaScript