preload.js

// -------------------------------------------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
// -------------------------------------------------------------------------------------------------

// based on answer from https://stackoverflow.com/questions/57807459/how-to-use-preload-js-properly-in-electron
const {
    contextBridge,
    ipcRenderer
} = require("electron");

// Expose protected methods that allow the renderer process to use
// the ipcRenderer without exposing the entire object
contextBridge.exposeInMainWorld(
    "api", {
        send: (channel, data) => {
            let validChannels = ["postFile", "selectFile", "getChangeFeed"];
            if (validChannels.includes(channel)) {
                ipcRenderer.send(channel, data);
            }
        },
        receive: (channel, func) => {
            let validChannels = ["filePosted", "fileSelected", "httpErrorEncountered", "errorEncountered", "success", "changeFeedRetrieved"];
            if (validChannels.includes(channel)) {
                // Deliberately strip event as it includes `sender` 
                ipcRenderer.on(channel, (event, ...args) => func(...args));
            }
        }
    }
);