JavaScript Regular Expression For Years

I am trying to write a regular expression to ensure that the text of years is valid. The following are ALL valid years

• 2023
• 300
• -1
• 40AD
• 40 AD
• 3000 BC
• 200BC

Here is the Regex that I camp up with

^(-?)([0-9]+)\s*(BC|AD){0,1}$

However it has one shortfall. The above Regex also finds a match for the following:

• -200AD
• -700BC
• 0BC
• 0AD
• -0
• -0BC
• -0AD

So bascially, I do NOT want the Regex to find a match if any of the following happens:

1. A negative number is enetered, with the letters BC or AD
2. 0BC or 0AD should not be allowed
3. -0 should not be allowed. This also then includes -0BC and -0AD, which in turn should not be allowed either

How do I do that?

Thanks.

Consider:

let re = String.raw`
    ^ # begin
    (
        (
            # negative
            -
            [1-9] [0-9]{0,3}  # dont allow leading zeroes
        )
        |
        (
            # positive
            [1-9] [0-9]{0,3}  # dont allow leading zeroes
            (
                # AD/BC
                \s*
                (AD | BC)
            )?
        )
        |
        (
            # special case
            0
        )
    )
    $ # end
`

//

re = new RegExp(re.replace(/\s+|#.+/g, ''))

console.log(re)
;
`
2023
300
-1
40AD
40 AD
3000 BC
200BC
-200AD
-700BC
0BC
0AD
-0
-0BC
-0AD
`.trim().split('\n').map(s => s.trim()).forEach(s => console.log(s, re.test(s)))

Regular expressions are programs, why do people insist on writing them without spaces and indentation? ;)