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Debugging Javascript

While you're working on all this code, it's helpful to have as much detail as you want available. So here are some recommendations to make developing & debugging a little easier within the NodeJS world.

Fast Reloads with Nodemon​

nodemon is a tool that will monitor your node app, and restart the app if it detects any changes in your code. This is already installed in your Milestone 2 project.

npm install --save nodemon

Usage:

nodemon app.js

Using the Debugger​

In the browser, you could use the Debugger from within Chrome Dev Tools and step through your code. You can replicate the same thing in VS Code, but it takes a couple of steps.

info

Note: For Milestone 2, copy and paste this gist into your .vscode/launch.json file in your repository:

https://gist.github.com/intricatecloud/8bf533380f335544063b45ef366604c0

  • This assumes that you have VSCode open to your milestone-2 project directory. So you should see backend/ and frontend/ in the VSCode Side Bar

You can then click on the Run & Debug panel in the Side Bar, and then select any of the scripts in the dropdown, depending on which tests you want to debug. For example, click on npm test-db to run the database.spec.js tests while being able to set breakpoints in VSCode.

Select npm start if you want to run your server with the ability to set breakpoints as well.

View Access Logs​

Similar to the Access Logs that we viewed from our web server for static websites, we can see similar traffic for our express server. We'll need to install a tool called morgan [link to docs]that can log this information to the console.

*This is already installed as part of your Milestone 2 project.

npm install --save morgan

and then add

app.js
import express from 'express'
import morgan from 'morgan'

app.use(express.json())
...
app.use(morgan(combined))

The next time you receive a request, you'll see this in your console:

App is running on port 8000
::1 - - [13/Mar/2023:03:03:30 +0000] "GET / HTTP/1.1" 200 11 "-" "PostmanRuntime/7.26.10"
::1 - - [13/Mar/2023:03:04:11 +0000] "GET /chatroom HTTP/1.1" 404 147 "-" "PostmanRuntime/7.26.10"