JavaScript code puzzle: convert a Boolean to Number

#javascript #puzzle #beginners

Write a function fn that receives a Boolean and returns it's representation as a Number. So true becomes 1 and false becomes 0.

Contstraints:

no Number constructor or any of it's prototype allowed
no Math functions allowed
no toNumber implementations allowed either
Strings of numbers, such as '1' and '0' do not count
Assume the function always receives a valid boolean (so no null or undefined or other types need to be considered).

Tests:

 console.assert(fn(true) === 1)
 console.assert(fn(false) === 0)

Note:

It's marked as #beginners, because it's solution easier than you might think.

Bonus:

It's possible to solve it with 9 characters overall.

Top comments (2)

Up to 3 characters:

const fn_not = b => ~~b;
const fn_inc = b => b++;
const fn_nry = b => +b; // might fall under `toNumber` implementation

Cool stuff, keep it up!

Another solution with same length would be

Spoiler

fn=b=>b/1

I counted the function too, which I came up to 9 characters