Regex match for specific number before but not after in javascript

Question

I just suck at regex. I've been reading at http://www.regular-expressions.info/tutorial.html but I can't figure out how to write this.

I have a string that contains 2 numbers (days of the month with leading 0s). I'm trying to remove the leading 0s from the string but not remove the 0 in "10" or "20".

example strings that could be here: "01","02","03","10","11","12","20","31"

since the string is always a day of the month, it will always be 2 characters in length and always between 01 and 31.

currently I'm using this (which is obviously wrong):

string.replace(/0/,'');

What I'm trying to end up with is this: "1" instead of "01", "2" instead of "02", "10" without losing the "0".

Hopefully this is clear enough.

How do I do this correctly?

Answer 1

If the string only contains the number you could just convert it to an integer, eg:

var num = +str;

If you want to replace parts of a larger string, you can use \\b :

str.replace(/\b0+\B/g, '');

Example:

"i have 000100 and 0020!".replace(/\b0+\B/g, '')

Returns:

"i have 100 and 20!"