chromite - Chrome Extension Messaging Routing Kit

• Use Router to simplify your onMessage event listener routing
• Use Client as a shorthand for sendMessage
• Use Logger for decorating console.log with intuitive interface

to write your Chrome Extension in the way of Web Application Development.

Why?

Message Passing plays a crucial role in the development of Chrome extensions. Therefore, as Chrome extensions become more feature-rich, the variety of messages being sent and received between the background and other contexts increases. Managing all of this within a single onMessage.addListener and dispatching to different handlers can make the code quite messy.

Which is like this:

// This is what we do usually... 😰
chrome.runtime.onMessage.addListener(async (message, sender, sendResponse) => {
  switch (message.action) {
    case '/users/list':
      const users = await Users.getAll()
      sendResponse({ users });
      break;
    case '/users/get':
      const user = await Users.get(message.userId);
      sendResponse({ user });
      break;
    case '/users/update':
      const user = Users.get(message.userId)
      // more your code here...
      break;
    default:
      sendResponse({ message: "Not Found..." });
  }
  return true;
});

This is very similar to what we write when we build a web application and routing HTTP request. Then, if we organize the code in that manner, we can create a Chrome extension source code that is more comprehensible and maintainable.

Router

Specifically, it would look like this:

const router = new Router();

router.on("/users/list", ListUsersController);
router.on("/users/{id}", GetUserController);
router.on("/users/{id}/update", UpdateUserController);
router.onNotFound(NotFoundController);

chrome.runtime.onMessage.addListener(router.listener());
// Simple! 🤗

then one of your controllers will look like this:

async function ListUsersController(message, sender) {
    const users = await Users.getAll();
    return { users }; // You don't even need sendResponse
}

async function GetUserController(this: {id: string}, message, sender) {
    // You can retrieve path parameter from `this` arg
    const user = await Users.get(this.id);
    return { user };
}

this will make our life easier.

Then simply you can send message to this listener like this:

const users = await chrome.runtime.sendMessage({action: '/users/list'});
// Nothing different to whant we do usually.

Client

In case you need some shorthand to send message, which might be a HTTP client in web application, there is Client you can use and you can avoid using action field in your message.

const client = new Client(chrome.runtime);

// path (=action) only
const users = await client.send('/users/list');

// path with request body
const updated = await client.send(`/users/${id}/update`, {name: "otiai20"});

ActiveRecord?

Now you might want something like ActiveRecord to access and OR-mapping chrome.storage. There is a separated package: jstorm - JavaScript ORM for chrome.storage and LocalStorage.

https://github.com/otiai10/jstorm

Small example:

// This uses window.sessionStorage
import { Model } from "jstorm/browser/session";

class User extends Model {
  public name: string;
  public age:  number;
}

(async () => {
  const otiai10 = User.new({name:"otiai10"});
  (otiai10._id) // null, yes
  await otiai10.save();
  (otiai10._id) // NOT null, because saved

  const found = await User.find(otiai10._id);
  (found._id == otiai10._id) // true

  otiai10.delete();
})();

Logger

Last but not least, logging is also important for us. Even though we know we can customize console.log by %c decorator, it would be messy if we do that all the time. Logger is just a memorandum for that decoration, or we can just use like following:

import {Logger, LogLevel} from "chromite";

const logger = new Logger("your_project", LogLevel.ERROR);

logger.warn("hello", 100, {name: "otiai10"});
// prints nothing because level is set to "ERROR"

// This prints these messages with colored prefix "[ERROR]"
logger.error("hey", {code: 500, msg: ["some", "problem"]});

Issues

• https://github.com/otiai10/chromite/issues/new