This is just to make sure it will return true or false haha

Теперь буду знать про every(

thank you for your suggestion :) (mine looks same as him)

woahhhhhhhh that is amazing

This is super clean.

good though

basically if true return true

This doesn't seem like the most practical approach.. don't know why it has most clever votes..

Yes, but my point was that this isn't best practice.. just clever.

the description says the input will be all positive integers

Good, but if they were to pass negative numbers as an input and it would fail..

I really dig the way the alphabet array was created here.

Yes, I did exactly what you say ,But in a more stupid way

if the specified substring ( a - z ) is not present in the given value ( string ), the indexOf() returns a negative value.