匹配号码，无小数，大于10,000

Question

I am not very familiar with regex and am trying to create a regex code in JavaScript to match a string with only

• whole numbers
• no decimals/dots
• and should be greater than 10,000

So far I have it like the ff. I think I am missing something as it still read through decimal numbers and == 10,000. How do I do that?

[1-9](?!\\.)\\d[0-9]{3,}

https://regex101.com/r/hG2iU7/61

Answer 1

At the risk of not directly answering the question, JavaScript can already parse numbers. Why bother trying to reimplement this? Especially with RegExp?

Why not just parseFloat(theString) or Number(theString) the entire string?

It will fail/return NaN if what you have isn't a number, and you can test for this with isNaN .

If it doesn't fail, you can then test it to ensure that it's an integral value:

const isIntegral = Math.trunc(theNumber) === theNumber;

and is less than 10000

const isLessThan10000 = theNumber < 10000;

This code is going to be much easier to read and maintain than a regular expression.

Answer 2

You may use

^[1-9][0-9]{4,}$

To exclude 10000 add a (?!10000$) lookahead:

^(?!10000$)[1-9][0-9]{4,}$
 ^^^^^^^^^^

See the regex demo and the regex graph :

Details

• ^ - start of string
• (?!10000$) - a negative lookahead that cancels the match if the whole string is equal to 10000 (ie after start of string ( ^ ), there is 10000 and then end of string position follows ( $ ))
• [1-9] - a digit from 1 to 9
• [0-9]{4,} - any four or more digits
• $ - end of string.