I've developed applications in JS, but don't have extensive experience with it, and I couldn't spot the problem. Frankly, I think if `['1', '2'].map(parseInt)` is both valid and does not result in a collection containing the integers 1 and 2 in that order, that indicates a catastrophic failure of design at some level. These things happen, but usually you have to dig down to a less bog standard example to find it. The "you just have to know" argument is often unavoidably valid, but in this case I think it's way off the mark.