Express

Perhaps the most popular NodeJS server-side framework, Express is used in thousands of projects. Exceptionless provides dedicated NodeJS support, and configuring your Exceptionless client in Express is easy.

Install #

To install exceptionless, you can use npm or yarn:

npm - npm install exceptionless

yarn - yarn add exceptionless

Initializing the Client #

With Exceptionless, you can initialize a default client which provides a singleton instance, or you can initialize a custom client. We'll go over the way to initialize each.

Default Client

const { ExceptionlessClient } = require('exceptionless/dist/exceptionless');
const client = ExceptionlessClient.default;
client.config.apiKey = 'YOUR API KEY';

With that set up, you can use the Exceptionless default client anywhere in your app in a number of ways. You can use hooks, you can use Redux, you can pass Exceptionless down through a higher-order component.

Custom Client

There are a variety of reasons you might want to instantiate a custom Exceptionless client. The custom client, for one, gives you more configuration options. Let's take a look at how to set it up.

const { ExceptionlessClient } = require('exceptionless/dist/exceptionless');
const config = {
  apiKey: "YOUR API KEY", 
  serverUrl: "YOUR SELF HOSTED URL",
  ...
};
const client = new ExceptionlessClient(config);

Simple Example #

In this example, we're just making use of the Exceptionless client in a file that handles one of our API routes.

const express = require("express");
const router = express.Router();
const { isAuthenticated } = require("./middleware");
const { ExceptionlessClient } = require("exceptionless/dist/exceptionless.node");
const config = {
  apiKey: "YOUR API KEY", 
  serverUrl: "YOUR SELF HOSTED URL", // Optional, leave blank if using hosted Exceptionless
  ...
};
const client = new ExceptionlessClient(config);

router.get("/:userId", isAuthenticated(client), async (req, res) => {
    try {
        const user = await fetchUserById(req.params.userId);        
        return res.status(200).json(user);
    } catch (error) { 
        client.createException(error).submit();   
        return res.status(500).send(error);
    }
});

module.exports = router;

You'll notice, we have an isAuthenticated middleware function that we are passing our client into. This is just one way to give middleware access to the Exceptionless client. In the next example, you'll see a global way of doing all of this.

In the route itself, we have a try/catch and we use our client to submit an exception if an error is triggered.

Global Example #

In the entry file for your Express app, which is normally server.js or app.js, we can declare our Exceptionless client the same way as above. Then, we can make use of the built-in Express

const express = require("express");
const PORT = 5200;
const { ExceptionlessClient } = require("exceptionless/dist/exceptionless.node");
const config = {
  apiKey: "YOUR API KEY"
};
const client = new ExceptionlessClient(config);

const app = express();

app.get("/", (req, res, next) => {
  res.status(200).send(missingVariable);
});

app.use((error, req, res, next) => {
  client.createException(error).submit();
  return res.status(500).json({ error: error.toString() });
});

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

In this example, it's important that your app.use handler for errors comes after your routes. This makes it so that uncaught errors will automatically be sent to Exceptionless and an error response will be sent back to the user.