Javascript中的正则表达式以大写开头，只有字母，maxlength 20，minlength 2

Question

I can validate this rule using plain Javascript. But I would prefer to do it using RegEx. I tried this (and other variations) but am not too confident:

  regEx = /^[A-Z]([a-z]|[A-Z]){1,19}$/;

Test cases did go through. Is this the right way or is there a better approach?

Answer 1

You may need a tool for build your regEx like https://regex101.com

What do you want to match exactly ?

Your regex match the following string: - Start by a character between [AZ] => only alphabetical upper case - 1 to 19 alphabetical character either upper or lower case

So your string length is between 2 and 20 characters.

You could simply your regExp by

regEx = /^[A-Z][a-zA-Z]{1,19}$/;

If you want no min length, mean that empty string match you could use:

regEx = /^([A-Z][a-zA-Z]{0,19})?$/

If you want min lenght to be 1, means that you match single upper character you could use:

regEx = /^[A-Z][a-zA-Z]{0,19}$/