@red please share with us your ++ code :D

Fail

++;

#include "devRant.h"

int main(){
while(true){
++;
}
return 0;
}

most basic version through chrome console:
open a user comments section or anything with a .plusone really and run:
document.querySelectorAll('.plusone').forEach(function(plus){ plus.click() })

@mpie I'm not familar with HTML/CSS/JS but following is your enhanced version:

document.querySelectorAll('.plusone').forEach(function(plus){
let parent = plus.closest(".vote-widget");
if(parent.classList.contains("vote-state-unvoted")){
plus.click();
}
});