Patabugen / FastMail Auto Save Drafts

// ==UserScript==
// @name         FastMail Auto Save Drafts
// @namespace    http://patabugen.co.uk/
// @version      0.1
// @description  Click on the Save Now button every 5 seconds when editing a draft in FastMail
// @author       Patabugen
// @match        https://www.fastmail.com/mail/compose/*
// @grant        none
// ==/UserScript==

/**
 * Fire an event handler to the specified node. Event handlers can detect that the event was fired programatically
 * by testing for a 'synthetic=true' property on the event object
 * @param {HTMLNode} node The node to fire the event handler on.
 * @param {String} eventName The name of the event without the "on" (e.g., "focus")
 * 
 * Taken from: http://stackoverflow.com/a/2381862
 */
function fireEvent(node, eventName) {
    // Make sure we use the ownerDocument from the provided node to avoid cross-window problems
    var doc;
    if (node.ownerDocument) {
        doc = node.ownerDocument;
    } else if (node.nodeType == 9){
        // the node may be the document itself, nodeType 9 = DOCUMENT_NODE
        doc = node;
    } else {
        throw new Error("Invalid node passed to fireEvent: " + node.id);
    }

    if (node.dispatchEvent) {
        // Gecko-style approach (now the standard) takes more work
        var eventClass = "";

        // Different events have different event classes.
        // If this switch statement can't map an eventName to an eventClass,
        // the event firing is going to fail.
        switch (eventName) {
            case "click": // Dispatching of 'click' appears to not work correctly in Safari. Use 'mousedown' or 'mouseup' instead.
            case "mousedown":
            case "mouseup":
                eventClass = "MouseEvents";
                break;

            case "focus":
            case "change":
            case "blur":
            case "select":
                eventClass = "HTMLEvents";
                break;

            default:
                throw "fireEvent: Couldn't find an event class for event '" + eventName + "'.";
                break;
        }
        var event = doc.createEvent(eventClass);
        event.initEvent(eventName, true, true); // All events created as bubbling and cancelable.

        event.synthetic = true; // allow detection of synthetic events
        // The second parameter says go ahead with the default action
        node.dispatchEvent(event, true);
    } else  if (node.fireEvent) {
        // IE-old school style
        var event = doc.createEventObject();
        event.synthetic = true; // allow detection of synthetic events
        node.fireEvent("on" + eventName, event);
    }
};

(function() {
    'use strict';
    
     function auto_save_draft()
    {
        var saveDraftButton = document.getElementsByClassName('s-save-draft')[0];
        if (saveDraftButton === undefined) {
            alert("Unable to find Save Draft button - auto save may not be working");
            return;
        }
        fireEvent(saveDraftButton, 'click');

        setTimeout(auto_save_draft, 5000);
    }
    // This partly just lets the page load, but there's also no need to save right away.
    setTimeout(auto_save_draft, 5000);
})();