The instructions don't say what the function is supposed to return. I assumed it wanted the index of the ball and I was right but it should say that.

No local test cases. Server-side test cases are hard to interpret to find the problem "ThereIsNoSpoonThereIsNoSpoon..." is hard to grok for potential issues in your algorithm.

Voting clever, because it is. Definitely not best practice: spec-wise, the order of keys in an object is undefined, so it's only by chance that V8's Object.keys happens to return the keys in order of definition. I love the hack, just want to point that out so that people don't rely on this for "actual" code.

Damn, can't believe I forgot about method chaining. I essentially did the same thing as this solution, but with each method on its own line. Your solution looks so much cleaner; I definitely voted Best Practice.

@ankr The problem is, .toString() is basically the same as .join(","). So you end up adding a load of commas you don't need, and then removing them. A simple .join("") would do the same with less work (as shown in the solution).

I guess the essentials are the same - although you could skip the i flag in your regex.

Excelente, best practice. I like codewars :D

My past solution, after the method sort(), pass the type Object toString() and replace with regex.
//code.split('').sort().toString().replace(/,/gi,'');