Measure Time from last click to page load

click-to-load-time.js

// ==UserScript==
// @name        Time from last click to page load
// @author      Zbigniew Tomczak
// @namespace   http://localhost/
// @version     2
// @grant       none
// ==/UserScript==

all : {
if (!window.localStorage) {
    console.log(" no local storage");
    break all;
}
if (window.localStorage.timeFromLastClick) {
    t = new Date().getTime() - window.localStorage.timeFromLastClick;
    //console.log(t + " ms (time spend from last click to page load)");
    document.body.innerHTML +=
        '<div title="Time spend from last click to page load (client time/browser time)" '
        +'style="position:absolute;width:135px;'
        +'height:30px;border-width:1px;'
        +'border-style:solid;border-color:grey;'
        +'border-radius: 0 0 5px 5px;padding-left:5px;'
        +'z-index:100;top:55px;left:1000px;font-size:10px;">'
        +'From click to page load:<br/>'+t+' ms.</div>';
    delete window.localStorage.timeFromLastClick;
}

if (document.onclick) {
    var oldOnClick = document.onclick;
}
document.onclick = function() {
    if (oldOnClick) {
        oldOnClick();
    }
    window.localStorage.timeFromLastClick;
    if (window.localStorage.timeFromLastClick) {
        window.localStorage.timeFromLastClick = new Date().getTime();
    } else {
        window.localStorage.timeFromLastClick = new Date().getTime();
    }
};
}