jQuery select based on text

I need to select an element based on its text in jQuery.

For instance:

<span>this text</span>

I know I can use .contains() to select based on text, but it's not exclusive.

I don't want to select:

<span>this text and that text</span>

I want to select the element if it's the only text of the element.

Aside from using regex, how do I do this with jQuery selectors?

Thanks.