I tried out the snippet... it works. It looks functional and easy to use. Perhaps for people looking at the code an unsure how to use it after loading you might include some other instructions on its use?
... Generally... an idea cannot be stolen (from above). As for whether or not this is borrowed from some other script that has popups I am not that widely versed to comment. While the code itself is not that advanced, I like the idea and the execution and I can see the thought that went into it. Unfortunately I am not a person who has an ability to officially rate your score.