sie schaffen der/die/das

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This is an 'unshift', not a 'push'.

Only if you keep the representation as in the description. But write it that way: null <- 3 <- 2 <- 1 and it suddenly becomes a push instead of an unshift. ;)

You're actually mixing up the basic vocabulary of linked lists/stacks (push = "add something to the head/on the top of the data structure") with the actual internal implementation where you could think about some sort of array where you'd insert the head at the index 0. And there you'd be doing unshift yes. Tho, "nothing" to do with the current task.

I'm having the same problem. I'm printing my variables to my test so I can see what's going on with the math. For some reason, the measurement for walking, which should be 132, is evaluating to 7.19999999 or something along those lines. I think that one of the tests is broken on the back end.

"If the walk is going to be over 2 hours, the function should recommend that you take the bus."

It's not correct.

Step|Hands
1 | 1 0 0
2 | 2 0 0
3 | 0 1 0
4 | 1 1 0
5 | 2 1 0
...

1. Just a bit
2. The little but wouldn't matter in pretty much all circumstances (if you need micro-optimization in JS, you're probably choosing the wrong language for the task)
3. And in the end, using these higher-order functions are much clearer and shorter than using for loops, so unless necessary you shouldn't even consider using for loops. No, slight performance gain is not an excuse to write longer, harder to read code.