RegExp to return true only when a character appears once. [Solved]

Question

Hi, i've been stuck trying to a solution to this:
Eg:
var str = "dre3fr@sft";
var str2 = " dre3fr@@sft";
var str3 = "dre3frsft";

I want a regEx that returns true only when a string contains (@) just once:

Expected output:
regEx.test(str); // true
regEx.test(str2); // false
regEx.test(str3); // false

Thanks in advance.

Answer 1

here is what I got that seems to work, I don't honestly think its the best so please correct me if I'm wrong.

^[^@]*@[^@]*$

the [^@] means anything but @.

Answer 2

Thank you @Apollo-Roboto.
That works. I got confused since I was trying to use quantifiers.