Installing packages (dependencies vs devDependencies) in Node.js - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to install a package as a regular dependency.

Node.js

npm install [1]

Drag options to blanks, or click blank then click option'

Aexpress

B--save-dev express

C--global express

D--save-exact express

Attempts:

3 left

💡 Hint

Common Mistakes

Using --save-dev installs the package as a devDependency instead of a regular dependency.

Adding --global installs the package globally, not locally.

To install a package as a regular dependency, just use npm install package-name without extra flags.

2fill in blank

medium

Complete the code to install a package as a development dependency.

Node.js

npm install [1]

Drag options to blanks, or click blank then click option'

A--save-dev jest

Blodash

C--global jest

D--save-exact jest

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the --save-dev flag installs the package as a regular dependency.

Using --global installs the package globally, which is not what you want here.

Use --save-dev to add a package only needed during development, like testing tools.

3fill in blank

hard

Fix the error in the command to install a devDependency.

Node.js

npm install [1]

Drag options to blanks, or click blank then click option'

A--save-dev

Bjest --save-dev

C--save-dev jest

D--dev jest

Attempts:

3 left

💡 Hint

Common Mistakes

Placing the package name before the flag causes an error.

Using --dev instead of --save-dev is invalid.

The correct syntax is npm install --save-dev package-name. The flag must come before the package name.

4fill in blank

hard

Fill both blanks to add a package as a regular dependency and save exact version.

Node.js

npm install [1] [2]

Drag options to blanks, or click blank then click option'

Aexpress

B--save-exact

C--save-dev

Dlodash

Attempts:

3 left

💡 Hint

Common Mistakes

Using --save-dev installs as a devDependency, not regular dependency.

Putting the flag before the package name can cause confusion.

Use npm install package-name --save-exact to install a regular dependency and save its exact version.

5fill in blank

hard

Fill all three blanks to install a package as a devDependency with exact version saved.

Node.js

npm install [1] [2] [3]

Drag options to blanks, or click blank then click option'

Ajest

B--save-dev

C--save-exact

Deslint

Attempts:

3 left

💡 Hint

Common Mistakes

Placing flags in the wrong order.

Using the wrong package name or missing flags.

The correct command is npm install --save-dev jest --save-exact to install jest as a devDependency and save its exact version.

Practice

1. Which command installs a package as a regular dependency needed to run your Node.js app?

easy

A. npm uninstall express

B. npm install --save-dev express

C. npm install express

D. npm update express

Solution

1. Step 1: Understand the difference between dependencies and devDependencies

   Dependencies are packages needed when your app runs, while devDependencies are only needed during development.

2. Step 2: Identify the correct npm command for dependencies

   The command npm install express installs the package as a regular dependency by default.

3. Final Answer:

   npm install express -> Option C

4. Quick Check:

   Regular dependencies use npm install without flags [OK]

Hint: Use plain npm install for runtime dependencies [OK]

Common Mistakes:

• Using --save-dev for packages needed at runtime
• Confusing uninstall with install commands
• Assuming npm update installs packages

2. Which of the following commands correctly installs a package as a development dependency?

easy

A. npm install lodash

B. npm install --save-dev jest

C. npm install --prod jest

D. npm install --global jest

Solution

1. Step 1: Recognize the flag for devDependencies

   The flag --save-dev tells npm to install the package as a development dependency.

2. Step 2: Match the command with the correct flag

   npm install --save-dev jest installs Jest as a devDependency, which is used for testing during development.

3. Final Answer:

   npm install --save-dev jest -> Option B

4. Quick Check:

   Dev dependencies use --save-dev flag [OK]

Hint: Use --save-dev flag for development-only packages [OK]

Common Mistakes:

• Omitting --save-dev for dev dependencies
• Using --prod which is not a valid flag for devDependencies
• Installing globally instead of locally

3. Given the following package.json snippet, which package will NOT be installed when running npm install --production?

{
  "dependencies": {
    "express": "^4.18.2"
  },
  "devDependencies": {
    "mocha": "^10.2.0"
  }
}

medium

A. mocha

B. express

C. both express and mocha

D. neither express nor mocha

Solution

1. Step 1: Understand the effect of --production flag

   The --production flag tells npm to install only the packages listed under dependencies, skipping devDependencies.

2. Step 2: Identify which packages are devDependencies

   Here, mocha is under devDependencies, so it will NOT be installed with npm install --production.

3. Final Answer:

   mocha -> Option A

4. Quick Check:

   DevDependencies skipped with --production flag [OK]

Hint: npm install --production skips devDependencies [OK]

Common Mistakes:

• Assuming all packages install regardless of flags
• Confusing dependencies with devDependencies
• Thinking --production installs devDependencies

4. You run npm install --save-dev eslint but later realize you need eslint as a regular dependency. What is the best way to fix this?

medium

A. Run npm install eslint to add it as a dependency

B. Run npm install --save-prod eslint

C. Manually edit package.json to move eslint from devDependencies to dependencies

D. Run npm uninstall eslint then npm install eslint

Solution

1. Step 1: Understand npm behavior with existing packages

   Running npm install eslint alone will not move it from devDependencies to dependencies if already installed as devDependency.

2. Step 2: Properly remove and reinstall as dependency

   Uninstalling first removes it from devDependencies, then reinstalling adds it to dependencies.

3. Final Answer:

   Run npm uninstall eslint then npm install eslint -> Option D

4. Quick Check:

   Uninstall then install moves package between dependency types [OK]

Hint: Uninstall then reinstall to change dependency type [OK]

Common Mistakes:

• Trying to install without uninstalling first
• Editing package.json manually without reinstalling
• Using non-existent --save-prod flag

5. You want to install webpack and babel packages. webpack is needed to run your app, but babel is only needed during development. Which commands correctly install them with proper dependency types?

hard

A. npm install webpack && npm install --save-dev babel

B. npm install webpack && npm install babel

C. npm install --save-dev webpack && npm install babel

D. npm install --save-dev webpack babel

Solution

1. Step 1: Identify runtime vs development packages

   Webpack is needed at runtime, so it should be a regular dependency. Babel is only for development, so it should be a devDependency.

2. Step 2: Use correct npm commands for each

   Use npm install webpack for runtime dependency and npm install --save-dev babel for development dependency.

3. Final Answer:

   npm install webpack && npm install --save-dev babel -> Option A

4. Quick Check:

   Runtime = npm install, Dev = npm install --save-dev [OK]

Hint: Install runtime normally, dev tools with --save-dev [OK]

Common Mistakes:

• Installing all packages as devDependencies
• Installing dev tools as regular dependencies
• Using --save-dev for runtime packages