In fact, this isn't about JavaScript, but that's the context I've discussed it in. I encourage you to think about it in more programming languages. (are there languages in which this can't be done?)
The problem: define functions range, map, reverse and foreach,
obeying the restrictions below, such that the following program works properly. It prints the squares of
numbers from 1 to 10, in reverse order.
var numbers = range(1, 10);
numbers = map(numbers, function (n) { return n * n });
numbers = reverse(numbers);
foreach(numbers, console.log);
/* output:
100
81
64
49
36
25
16
9
4
1
*/
Restrictions
You must not use arrays. The square bracket characters,
[and], are forbidden, as well asArrayconstructor.You must not use objects. The curly braces,
{and}, and the dot character (.) are forbidden. You may use curly braces for code blocks, but not for creating JavaScript objects.Should go without saying, these functions must be generic and do what their name implies. They must not be hard-coded for the particular
1..10example.
Feel free to define utilities; you don't have to restrict your program to these 4 functions. It does not matter how fast, small or elegant it is — if you can do it within the limitations above, I think you're an above-average programmer and I would probably hire you. (however: I'm not hiring)
Just for reference, my implementation (in ES6) is 8 lines of code, and it isn't totally unreadable. :-)
PS: please don't post your solutions, or links, here. I will not publish them. But feel free to email me in private if you really want me to look into it.