Regex to match only if symbol in string used once

Question

Maybe it's a simple question but today i'm a bit stucked with it.

I need regex to match only if symbol % appeared once in a string..

for example:

/regexpForSymbol(%)/.test('50%') => true
/regexpForSymbol(%)/.test('50%%') => false

Thanks!

Answer 1

You could use:

^[^%]*%[^%]*$

The anchors are there to ensure every character is covered, and you probably already know what [^%] does.