Exposes factoryidle.com's main game instance

factoryidleexposer.user.js

// ==UserScript==
// @name         Factoryidle Game Instance Exposer
// @namespace    SReject/FactoryIdle/Exposer
// @version      0.0.1
// @description  Exposes factoryidle.com's Game instance
// @author       SReject
// @match        http*://factoryidle.com/
// @match        http*://www.factoryidle.com/
// @run-at       document-start
// ==/UserScript==

/*
To reference the main game instance
you can reference the created global object:
MainInstance

or require() it as you would a typical requirejs module:
require(["mainGameInstance"], function (mainGameInstance) {
console.log(mainGameInstance);
});
*/

(function() {
    const FI_SCRIPT = 'http://factoryidle.com/app.js';

    // modifies factoryidle.com/app.js game script to expose
    const loadModifiedScript = () => {
        fetch(FI_SCRIPT).then((response) => {
            return response.text();
        }).then((res) => {

            // Add declarations for requirejs, require, define and MainInstance
            // to the start of the script
            let modifiedScript = 'var requirejs,require,define,MainInstance;';

            // Remove the internal declarations of requirejs, require, and
            // define to make them globally available
            modifiedScript += res.replace(/var\s+requirejs,\s*require,\s*define\s*;/, '');

            // Remove the internal declaration of MainInstance to make it
            // globally available
            modifiedScript = modifiedScript.replace(/var MainInstance,/, 'var ');

            // Add the game's main instance(MainInstance) as a requirejs module
            modifiedScript = modifiedScript.replace(/(define\("app",[^;]*;)/, '$1define(\'mainGameInstance\',()=>MainInstance);');

            // Create a new script node
            // add the modified script as its source
            let node = document.createElement('script');
            node.appendChild(document.createTextNode(modifiedScript));

            // if the page has finished initial loading (document.head is
            // available), append the modified script to document.head
            if (document.readyState === "interactive" || document.readyState === "complete") {
                document.head.appendChild(node);

                // otherwise, wait for the page to finish initial loading then append
                // modified script to document head
            } else {
                document.addEventListener('DOMContentLoaded', function handler() {
                    document.removeEventListener('DOMContentLoaded', handler);
                    document.head.appendChild(node);
                });
            }
        });
    };

    // (Chrome) Stop factoryidle's app.js from loading
    // Chrome doesn't support the beforescriptexecute event, so trap the loading
    // of the game script using MutationObserver
    if (navigator.userAgent.toLowerCase().indexOf('chrome') > -1) {

        // create a new MutationObserver
        const observer = new MutationObserver((mutations) => {

            // loop over the list of mutations that occured
            for (let mutation of mutations) {

                // if the mutation in question is a list of nodes added to the document
                if (mutation.type === 'childList' && mutation.addedNodes && mutation.addedNodes.length) {

                    // loop over each node added
                    Array.from(mutation.addedNodes).find((node) => {

                        // If the node added was not the game script, ignore it
                        if (node.tagName === undefined) return false;
                        if (String(node.tagName).toLowerCase() !== 'script') return false;
                        if (String(node.src).toLowerCase() !== FI_SCRIPT) return false;

                        // if the node is the game script, disconnect the observer
                        // and reset the node's src property so the game script
                        // isn't executed
                        observer.disconnect();
                        node.src = '';

                        // Attempt to load the modified script
                        loadModifiedScript();
                    });
                }
            }
        });

        // watch for ONLY nodes to be added/removed
        observer.observe(document.documentElement, {
            childList: true,
            subtree: true,
            attributes: false,
            characterData: false
        });

        // (firefox) Stop factoryidle's app.js load via beforescriptexecute event
    } else {

        // listen for the document to emit beforescriptexecute events
        document.addEventListener('beforescriptexecute', function handler(evt) {

            // check that the script is the game's script
            if (evt.target.src == FI_SCRIPT) {

                // prevent the script from executing
                evt.preventDefault();

                // remove the listener
                document.removeEventListener('beforescriptexecute', handler);

                // attempt to load the modified script
                loadModifiedScript();
            }
        }, true)
    }
}());