Regular Expression - How to invert into NOT

Question

I am trying to write a regular expression which I can chain a few not rules together. I need to validate a number string to check that it does NOT match a few rules.

I need it to:

1. Not start with 3 zeroes
2. Not end with 4 zeroes
3. Not be all the same digit

Here is what I'm trying so far:

var re = new RegExp(/^(.)\1{8}$|^000|0000$/);

re.test("111111111"); // true; all same digit
re.test("000112222"); // true; starts with zeroes
re.test("111110000"); // true; ends in zeroes
re.test("123456789"); // false
re.test("111223344"); // false

This works for the first three cases by yielding TRUE, how can I invert the test to have it be false unless it meets the 3 rules?

(I know I can just flip it in the JS with a ! , I'm looking for a regex solution)

Answer 1

Putting all rules together, you can use this regex:

/^(?!0{3})(?!.*0{4}$)(\d)(?!\1*$)\d*$/gm

RegEx Demo

RegEx Breakup:

^           # start
(?!0{3})    # negative lookahead to assert failure when we have 3 0s at start
(?!.*0{4}$) # negative lookahead to assert failure when we have 4 0s at end
(\d)        # match a digit and capture in group #1
(?!\1*$)    # negative lookahead to assert we don't have same digit until end 
\d*         # match zero or more digits
$           # end