Alexander Pushkarev

function pos(e) {
    console.log(e.clientX);
}
function show(e) {
    pos(e);
}
document.body.addEventListener("click", show);

wp-admin
wp-includes

if (window.navigator.userAgent.indexOf("OPR") > -1 || window.navigator.userAgent.indexOf("Opera") > -1) {
   // ...
}

if (window.opera && opera.toString() == "[object Opera]"){
   // ...
}