The same code written with if conditions will have very similar text, will be slightly longer, have a possibility of 'return' statements anywhere in the text, and more importantly - might have embedded mutations.
But personally, every identifier being a 'const' instead of a 'let' helps me reason about it much better, especially when the code is purely algorithmic. An alternative might be to use something like Facebook's Reason, where such code can be concise and idiomatic.