Regex not start in zero if single digit

Question

I have a 5 textboxes that can input only numbers. I used /^[1-9][0-9]+$/, but what I need is if single digit is zero allow it.

Just like the picture above, I have 5 textboxes if 1 of the textbox is already equal the quantity the other textbox should allow a zero value. It can't be greater or lower than in quantity.

Answer 1

Try a or condition

/^([1-9][0-9]*|0)$/

Answer 2

Your best bet is:

/^\d+$/

Which will allow only a number of one or more digits.

Breakdown

/ start of regex
^ matches beginning of string
\d matches any digit
+ modifies the above to match one or more
$ matches the end of line
/ ends the regex