What is the regex for “Any positive integer, excluding 0” [duplicate]

Question

There is already an other post for this but i can't comment on it. Sorry for that.

I used

var pattern = new RegExp('^[1-9]\d*$'); 
var result = fieldValue.search(pattern);

but i get a "-1" if I put 12

It allows me just number from 1 to 9 and no more.

Is there something wrong?

Answer 1

Assuming the language is JavaScript, you need to escape the backslash character within a string for it to have a value of backslash:

'\d' is a string with a value of d
'\\d' is a string with a value of \d

var pattern = new RegExp('^[1-9]\\d*$');

JavaScript also has regular expression literals, which avoid the need for additional escape characters:

var pattern = /^[1-9]\d*$/;

Answer 2

If you wanted to extend this to allow for positive integers with leading zeros, you could do this:

var pattern = /^\d*[1-9]+\d*$/

This will allow 001 as a valid input (which it is), while not allowing 000 (which is not non zero).