Userscript to subscribe to threads at www.cfd-online.com/Forums/ with a single click

add_button.js

// ==UserScript==
// @name        Add one-click subscription button
// @description Adds live example button, with styling.
// @include     http://www.cfd-online.com/Forums/*.html
// @require     http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js
// @grant       GM_addStyle
// @grant       GM_openInTab
// @version     0.0.1
// ==/UserScript==

// Based on https://stackoverflow.com/questions/6480082/add-a-javascript-button-using-greasemonkey 
// and https://stackoverflow.com/questions/5036737/how-do-you-make-greasemonkey-click-a-link-that-has-specified-text

/* If link to subscribe exists then show button */
var TargetLink = $("a:contains('Subscribe to this Thread')")

if (TargetLink.length) {
    /*--- Create a button in a container div.  It will be styled and
        positioned with CSS.
    */
    var zNode       = document.createElement ('div');
    zNode.innerHTML = '<button id="subscriptionButton" type="button">'
                    + 'Subscribe to this thread</button>'
                    ;
    zNode.setAttribute ('id', 'myContainer');
    document.body.appendChild (zNode);
    //--- Activate the newly added button.
    document.getElementById ("subscriptionButton").addEventListener (
        "click", ButtonClickAction, false
);
}


document.addEventListener('keydown', function(e) {
  // pressed alt+shift+ctrl+s
  if (e.keyCode == 83 && e.shiftKey && e.ctrlKey && e.altKey && !e.metaKey) {
    ButtonClickAction(null);
  }
}, false);


function ButtonClickAction (zEvent) {
    /*--- For our dummy action, we'll just add a line of text to the top
        of the screen.
    */
    var TargetLink = $("a:contains('Subscribe to this Thread')")

    if (TargetLink.length)
        GM_openInTab(TargetLink[0].href);
//        window.location.href = TargetLink[0].href
}

//--- Style our newly added elements using CSS.
GM_addStyle ( multilineStr ( function () {/*!
    #myContainer {
        position:               fixed;
        top:                    0;
        left:                   0;
        font-size:              20px;
        background:             orange;
        border:                 3px outset black;
        margin:                 5px;
        opacity:                0.9;
        z-index:                222;
        padding:                5px 20px;
    }
    #subscriptionButton {
        cursor:                 pointer;
    }
    #myContainer p {
        color:                  red;
        background:             white;
    }
*/} ) );

function multilineStr (dummyFunc) {
    var str = dummyFunc.toString ();
    str     = str.replace (/^[^\/]+\/\*!?/, '') // Strip function () { /*!
            .replace (/\s*\*\/\s*\}\s*$/, '')   // Strip */ }
            .replace (/\/\/.+$/gm, '') // Double-slash comments wreck CSS. Strip them.
            ;
    return str;
}

confirm_subscription.js

// ==UserScript==
// @name        OneClickSubscription
// @namespace   oneclicksubscription
// @description Subscribe to a thread on cfd-online.com with one click
// @include     http://www.cfd-online.com/Forums/subscription.php?do=addsubscription&t=*
// @version     0.0.1
// @grant       none
// ==/UserScript==

function main() {
    //alert('forms.length: ' + document.forms.length);

    for (var i = 0; i < document.forms.length; i++) {
        var action = document.forms[i].action;
        if (action.indexOf("doaddsubscription") > -1) {
            window.console.log("found form!");
            document.forms[i].submit();
        }
    }
}

main();