Regular Expression Repeating Pattern separated by comma
regex
Solution
Some of the other answers are repeating the lookahead assertions. That's not necessary.
Here's a regular expression that matches a comma-separated sequence of atoms, where each atom is four alphanumeric characters:
^[A-Z0-9]{4}(?:,[A-Z0-9]{4})*$
Of course, that's not quite what you want. You don't want atoms that are all alphabetic. Here's a negative lookahead assertion that prevents matching such an atom anywhere in the text:
(?!.*[A-Z]{4})
And you don't want atoms that are all numeric either:
(?!.*[0-9]{4})
Putting it all together:
^(?!.*[A-Z]{4})(?!.*[0-9]{4})[A-Z0-9]{4}(?:,[A-Z0-9]{4})*$
Problem
I have a regular expression of the following: ``` .regex(/^(?!^[0-9]*$)(?!^[a-zA-Z]*$)^([a-zA-Z0-9]{4})$/) ``` Must be exactly 4 characters Must contain at least 1 numeric and 1 alpha Although I rarely do regular expression, this was relatively easy. I now have a new requirement that I have tried to implement, but cannot get right. New requirement: Be able to have a comma separated list of the same type of input as before. Cannot end with a comma. Each item must be valid per the rules above (4 characters, at least on numeric, at least one alpha) ``` Valid: 123F,U6Y7,OOO8 Invalid: Q2R4, Invalid: Q2R4,1234 Invalid: Q2R4,ABCD Invalid: Q2R4,N6 ``` I very much appreciate your help! Thanks!