Youtube: I'm feeling lucky

Add I'm feeling lucky button to Youtube
当前为 2015-11-05 提交的版本，查看最新版本。
换行
// ==UserScript==
// @name         Youtube: I'm feeling lucky
// @namespace    http://tampermonkey.net/
// @version      1.0.2
// @description  Add I'm feeling lucky button to Youtube
// @author       divide100
// @match        http*://www.youtube.com/*
// @grant        GM_openInTab
// @require https://greasyfork.org/scripts/5679-wait-for-elements/code/Wait%20For%20Elements.js?version=46106
// ==/UserScript==
/* jshint -W097 */
'use strict';

var util = {
    log: function () {
        var args = [].slice.call(arguments);
        args.unshift('%c' + SCRIPT_NAME + ':', 'font-weight: bold;color: purple;');
        console.log.apply(console, args);
    },
    q: function(query, context) {
        return (context || document).querySelector(query);
    },
    qq: function(query, context) {
        return [].slice.call((context || document).querySelectorAll(query));
    },
    xmlReq: function(url, cb){
        var xhr = new XMLHttpRequest();
        xhr.open('get', url, true);
        xhr.responseType = 'document';
        xhr.onload = cb;
        xhr.send();
    }
};

var SCRIPT_NAME = "Youtube's feeling lucky";
var SEARCH_SEL = '#masthead-search';

util.log('Starting');

waitForElems(SEARCH_SEL, function(searchBar) {
    var btn = util.q('button', searchBar).cloneNode(true);
    var searchCrit = util.q('input', searchBar);
    btn.childNodes[0].textContent = 'Feelin\' Lucky';
    btn.childNodes[0].className = '';
    btn.onmousedown = function(e) {
        if(e.button === 1) {
            e.preventDefault();
        }
    }
    btn.onclick = function(e) {
        e.preventDefault();
        var strCrit = searchCrit.value;
        if(strCrit) {
            util.xmlReq('https://www.youtube.com/results?search_query=' + strCrit.split(' ').join('+'), function(xhe) {
                if(e.button === 1) {
                    GM_openInTab(util.q('.item-section a', xhe.target.response.body).href, false);
                }
                else {
                    window.location.href = util.q('.item-section a', xhe.target.response.body);
                }
            });
        }
        return false;
    };
    //util.log(btn);
    searchBar.insertBefore(btn, searchBar.firstChild);
});