npm initialization and package.json in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the main purpose of the package.json file in a Node.js project?

Choose the best description of what package.json does in a Node.js project.

A It contains the database configuration for the project.

B It lists the project dependencies, scripts, and metadata like name and version.

C It is used to compile JavaScript into machine code.

D It stores the actual code files of the project.

💡 Hint

Think about what npm needs to know to install packages and run scripts.

The package.json file holds important info about the project such as its name, version, dependencies, and scripts. It helps npm manage packages and run commands.

📝 Syntax

intermediate

Which command correctly initializes a new package.json with default values?

Select the npm command that creates a package.json file quickly with default answers.

A npm init

B npm start

C npm init -y

D npm install

💡 Hint

Look for the command that skips questions and uses defaults.

npm init -y creates a package.json file with default values without asking questions.

❓ component_behavior

advanced

What happens when you run npm install in a folder with a package.json but no node_modules folder?

Choose the correct behavior of npm when installing packages based on package.json.

A npm downloads and installs all dependencies listed in package.json into node_modules.

B npm deletes the package.json file and creates a new one.

C npm runs the start script defined in package.json without installing anything.

D npm throws an error because node_modules folder is missing.

💡 Hint

Think about what npm does to prepare the project environment.

When npm install runs, it reads package.json and downloads all dependencies into a new node_modules folder if it doesn't exist.

🔧 Debug

advanced

What error will occur if package.json has a trailing comma after the last property?

Identify the error npm shows when package.json contains a trailing comma in JSON syntax.

Node.js

{
  "name": "myapp",
  "version": "1.0.0",
  "dependencies": {
    "express": "^4.17.1"
  }
}

A SyntaxError: Unexpected token } in JSON at position ...

B TypeError: Cannot read property 'dependencies' of undefined

C Warning: Deprecated package.json format

D No error, npm ignores trailing commas

💡 Hint

JSON does not allow commas after the last item in an object or array.

Trailing commas in JSON cause a syntax error because JSON syntax is strict. npm will fail to parse package.json and show a SyntaxError.

❓ state_output

expert

After running npm init -y, what is the value of the scripts.test property in package.json?

Select the default command npm sets for the test script after quick initialization.

A npm run build

B node server.js

C node index.js

D echo "Error: no test specified" && exit 1

💡 Hint

Think about what npm does if you haven't defined a test script yet.

By default, npm init -y sets the test script to a command that prints an error and exits, indicating no test script is defined.