Regex: only alphanumeric but not if this is pure numeric

Question

For instance:

'1'     => NG
'243'   => NG
'1av'   => OK
'pRo'   => OK
'123k%' => NG

I tried with

 /^(?=^[^0-9]*$)(?=[a-zA-Z0-9]+)$/

but it is not working very well.

Answer 1

So we know that there must be at least one "alphabetic" character in there somewhere:

[a-zA-Z]

And it can have any number of alphanumeric characters (including zero) either before it or after it, so we pad it with [a-zA-Z0-9]* on both sides:

/^[a-zA-Z0-9]*[a-zA-Z][a-zA-Z0-9]*$/

That should do the trick.