Async control flow "library"

Regarding:

for (var i in ["a","b","c"]) console.log(i)
"a"
"b"
"c"

This is incorrect. for-in will assign the value of the "key" (in this case the numeric index) to i, not the property "value".

This is correct:

for (var i in ["a","b","c"]) console.log(i)
0
1
2