Adds links to Queue and Jobs for killing all of them. Be aware - as soon as you click the links, all currently shown jobs or queues will be cancelled without asking.

jenkins-kill-jobs.user.js

// ==UserScript==
// @name         Jenkins kill BuildQueue + Jobs
// @namespace    https://jenkins
// @version      0.32
// @description  Adds a link to Queue and Jobs for killing all of them.
// @author       Markus Edenhauser
// @include      /^https://jenkins*/
// @exclude      *configure
// @grant        none
// @require http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js
// ==/UserScript==

(function() {
    var cancelWaitTime = 150;
    var currentTime = 0;

    jQuery('body').prepend('<style>body { background-color: #eee; }; </style>');
 
 var jenkinsPath = location.protocol + '//' + location.host;
 var makeid = function() {
    var text = "";
    var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    for( var i=0; i < 5; i++ )
        text += possible.charAt(Math.floor(Math.random() * possible.length));

    return text;
 };
 var settings = {
  "async": true,
  "crossDomain": true,
  "url": null,
  "method": "POST",
  "headers": {
    "accept": "text/javascript, text/html, application/xml, text/xml, */*",
    "x-prototype-version": "1.7",
    "x-requested-with": "XMLHttpRequest",
    "content-type": "application/x-www-form-urlencoded; charset=UTF-8",
    "cache-control": "no-cache"
  }
};

var killQueue = function(baseLink, selector){
     console.log('tampermonkey - killing ' + jQuery(selector).length + ' jobs');
     jQuery(selector).each(function(elem, index){
         var onClickContent = jQuery(this).attr('onclick');
         if(onClickContent.indexOf('null') !== -1) {
             console.log('skipped already canceled item.');
             return;
         }
         var targetHref = jQuery(this).attr('href');
         console.log('queued', targetHref);
         settings.url = baseLink + targetHref;
         currentTime = currentTime + cancelWaitTime;
         setTimeout(function(sett) {
             console.log('killing', targetHref);
             jQuery.ajax(sett).done(function(response) { console.log('done'); });
         }(settings), currentTime);
     });
 };
var addKillLink = function(selector, prependSelector, linkText, baseLink) {
    var newSelect = makeid();
    jQuery(prependSelector).prepend('<a class="collapse ' + newSelect + '" style="cursor:pointer">' + linkText + '</a>');
    jQuery('.' + newSelect).on('click', function() { killQueue(baseLink, selector); });
};

var buildQueueSelector = '#buildQueue .pane-header';
if(jQuery(buildQueueSelector).length) {
  addKillLink('#buildQueue .stop-button-link', buildQueueSelector, 'Kill Queue!', jenkinsPath);
}
var executorsSelector = '#executors .pane-header';
if(jQuery(executorsSelector).length) {
    addKillLink('#executors .stop-button-link', executorsSelector, 'Kill Jobs!', jenkinsPath);
}

})();