正则表达式允许带前导零的数字

Question

My requirement is that I should pass 4 or more "digits" and fail the rest. The regex I used is:

var test = new RegExp(/[0-9]{4,100}$/);

However, numbers with leading zeros like 0001 or 0123 fail. How can I modify the regex to allow for numbers with leading zeros while sticking to my requirement. Thanks!

Answer 1

Make sure you have quotes around the number you're testing. The syntax is:

RegExpObject.test(string)

var test = new RegExp(/[0-9]{4,100}$/);

This returns false because it is interpreted as the number 9:

test.test(000009);

The leading zeros are ignored.

This returns true because the whole string is considered:

test.test('000009');

Answer 2

Use the follwoing regex to find numbers that do not start with zeros:

\b[1-9]\d{3,}

DEMO