lastly is a lightweight, no-dependency Node.js library sending a final error via POST to an absolute url.

When your program encounters an uncaught exception lastly takes over. Lastly follows the same rules for error handling as process.on('uncaughtException', error => {}) so it will only handle runtime errors. If you had an error in your syntax, for example, then you'll need to fix your code the hard way! Currently, lastly will only send a POST request formatted like a Slack message. It is important to mention that if you currently have the aforementioned uncaughtException process event set up you will need to wrap that inside of lastly's callback function.

If you are sending to a Slack incoming webhook then setup is very simple. You can provide an optional callback if you want to do something with the error after lastly processes it.

It is important that lastly is configured before en error is thrown. For this reason I suggest you configure lastly as early as you can in your project

Lastly has only one required parameter, an absolute URI. It can optionally take a second parameter, a callback function, that will return the error that lastly processed.

const lastly = require('lastly')
lastly('https://hooks.slack.com/services/XXXXX/XXXXX/xxxxxxxxxx');

const lastly = require('lastly')
lastly('https://hooks.slack.com/services/XXXXX/XXXXX/xxxxxxxxxx', (err) => {
  // Handle err
  console.error(err);
});

If you are using the Express library you may want to handle errors that are caught by Express. To do this you'll use the error handler that lastly creates during setup and use it as middleware after all of your routes have been declared.

const lastly = require('lastly');
const express = require('express');
const PORT = process.env.PORT || 8081;

const errorHandler = lastly('https://hooks.slack.com/services/XXXXX/XXXXX/xxxxxxxxxx');

app.get('/', (_req, res) => {
  res.send('Lastly is awesome!');
});

app.use(errorHandler);

app.listen(PORT, () => console.log(`Listening on port ${PORT}...`));