Why 0 is being excluded ?

Question

Guys, i’m doing an javascript exercise and i got doubious. When i transformed the number following by 0 to string by adding with empty string, and then output the length.

Why the length is not 5 ??
https://code.sololearn.com/W987q2v8qXt4/?ref=app

Answer 1

There is no number start with 0, so it should be 4.
If you want 5, you have to declare it to string like
'02344'

Good Luck ~

Answer 2

"Never write a number with a leading zero (like 07).
Some JavaScript versions interpret numbers as octal(base 8) if they are written with a leading zero." quote from W3Schools
https://www.w3schools.com/js/js_numbers.asp;

https://code.sololearn.com/Wk3c5vbCl6L2/#html