Nodemon for development reloading in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Nodemon in the context of Express development?

Nodemon is a tool that automatically restarts your Express server whenever it detects file changes. This helps developers see updates immediately without manually stopping and starting the server.

beginner

How do you install Nodemon for your Express project?

You install Nodemon by running npm install --save-dev nodemon. This adds Nodemon as a development dependency, so it is only used during development.

beginner

How can you start your Express app using Nodemon?

You can start your app with Nodemon by running npx nodemon app.js or by adding a script in package.json like "start:dev": "nodemon app.js" and then running npm run start:dev.

beginner

Why is Nodemon useful compared to manually restarting the server?

Nodemon saves time and effort by watching your files and restarting the server automatically. This means you can focus on coding without interrupting your workflow to restart the server each time you make a change.

intermediate

Can Nodemon watch specific file types or folders only?

Yes, Nodemon can be configured to watch specific files or folders by using a nodemon.json file or command line options. For example, you can watch only JavaScript files or exclude certain folders to optimize reloading.

What does Nodemon do when it detects a file change in your Express app?

A Automatically restarts the server

B Deletes the changed file

C Sends an email notification

D Compiles the code into a binary

Nodemon watches for file changes and restarts the server automatically to reflect updates.

How do you add Nodemon as a development tool in your project?

A npm start nodemon

B npm install --save-dev nodemon

C npm uninstall nodemon

D npm install nodemon --global

Installing with --save-dev adds Nodemon as a development dependency.

Which command runs your app with Nodemon without installing it globally?

A nodemon start

B node app.js

C npm run nodemon

D npx nodemon app.js

Using npx runs Nodemon from your local node_modules without global install.

What file can you create to customize Nodemon's behavior?

A nodemon.json

B nodemon.config.js

C package-lock.json

D express.json

nodemon.json lets you specify files to watch, ignore, and other settings.

Why might you want to exclude some folders from Nodemon watching?

A To make Nodemon run slower

B To delete those folders automatically

C To reduce unnecessary restarts and improve performance

D To prevent Nodemon from starting

Excluding folders like node_modules avoids restarts triggered by irrelevant changes.

Explain how Nodemon improves the development experience when working with Express apps.

Think about what happens when you change code and how Nodemon helps.

Describe the steps to set up Nodemon in a new Express project.

Focus on installation, running, and configuration.

Practice

1. What is the main purpose of using nodemon in an Express development environment?

easy

A. To create a database connection automatically

B. To minify JavaScript files for production

C. To deploy the Express app to a cloud server

D. To automatically restart the server when code changes are detected

Solution

1. Step 1: Understand what nodemon does

   Nodemon watches your Node.js files and restarts the server automatically when it detects changes.

2. Step 2: Compare options with nodemon's purpose

   Options B, C, and D describe tasks unrelated to nodemon's automatic restart feature.

3. Final Answer:

   To automatically restart the server when code changes are detected -> Option D

4. Quick Check:

   Nodemon = auto-restart server on changes [OK]

Hint: Nodemon restarts server automatically on file changes [OK]

Common Mistakes:

• Thinking nodemon deploys the app
• Confusing nodemon with build tools
• Assuming nodemon manages databases

2. Which command correctly starts an Express app using nodemon for automatic reloading?

easy

A. node nodemon app.js

B. nodemon app.js

C. nodemon start app.js

D. start nodemon app.js

Solution

1. Step 1: Recall the correct nodemon command syntax

   The correct way to start nodemon is by running nodemon followed by the file name, e.g., nodemon app.js.

2. Step 2: Check each option's syntax

   node nodemon app.js incorrectly prefixes with node. nodemon start app.js adds an invalid start keyword. start nodemon app.js reverses the order incorrectly.

3. Final Answer:

   nodemon app.js -> Option B

4. Quick Check:

   Correct nodemon command = nodemon filename [OK]

Hint: Use 'nodemon filename.js' to start with auto-reload [OK]

Common Mistakes:

• Adding 'node' before nodemon
• Using extra keywords like 'start'
• Swapping command order

3. Given the following command run in terminal: nodemon server.js, what happens when you save changes to server.js?

medium

A. The server automatically restarts to apply the changes

B. The server crashes and needs manual restart

C. Nothing happens until you manually restart the server

D. Nodemon deletes the server.js file

Solution

1. Step 1: Understand nodemon's behavior on file changes

   Nodemon watches the specified file and restarts the Node.js server automatically when it detects a save or change.

2. Step 2: Analyze the options

   The server automatically restarts to apply the changes correctly describes the automatic restart. Options A and B describe manual intervention or crashing, which nodemon prevents. Nodemon deletes the server.js file is incorrect and harmful.

3. Final Answer:

   The server automatically restarts to apply the changes -> Option A

4. Quick Check:

   Save file triggers auto-restart = nodemon feature [OK]

Hint: Saving watched files triggers nodemon restart automatically [OK]

Common Mistakes:

• Thinking nodemon crashes server on changes
• Believing manual restart is always needed
• Confusing nodemon with file deletion

4. You run nodemon app.js but the server does not restart after you save changes. What is the most likely cause?

medium

A. All of the above

B. Nodemon is not installed globally or locally

C. The app.js file has syntax errors preventing restart

D. You forgot to save the file after editing

Solution

1. Step 1: Check nodemon installation

   If nodemon is not installed, the command won't work properly, so no restart happens.

2. Step 2: Verify file saving and syntax

   If the file is not saved, nodemon won't detect changes. Syntax errors can cause the server to crash and fail to restart.

3. Step 3: Combine all causes

   All these issues can prevent nodemon from restarting the server automatically.

4. Final Answer:

   All of the above -> Option A

5. Quick Check:

   Installation, saving, syntax errors all affect nodemon restart [OK]

Hint: Check install, save file, and syntax if nodemon won't restart [OK]

Common Mistakes:

• Ignoring nodemon installation status
• Assuming nodemon restarts without saving
• Overlooking syntax errors blocking restart

5. You want nodemon to watch both server.js and all files in the routes folder for changes. Which command correctly achieves this?

hard

A. nodemon --watch server.js routes

B. nodemon server.js routes

C. nodemon --watch server.js --watch routes server.js

D. nodemon --watch server.js --watch routes/

Solution

1. Step 1: Understand nodemon's --watch option

   The --watch flag tells nodemon which files or folders to monitor for changes.

2. Step 2: Analyze the options

   nodemon --watch server.js --watch routes server.js correctly uses multiple --watch flags to monitor both and specifies server.js as the script (trailing slash on folders optional). nodemon server.js routes passes extra arguments incorrectly. nodemon --watch server.js routes misses --watch for the folder. nodemon --watch server.js --watch routes/ misses the entry script to execute.

3. Final Answer:

   nodemon --watch server.js --watch routes server.js -> Option C

4. Quick Check:

   Use multiple --watch flags followed by script [OK]

Hint: Use multiple --watch flags followed by the entry script [OK]

Common Mistakes:

• Passing folder without --watch
• Omitting the entry script
• Adding extra arguments after filename