Why modules are needed in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the module correctly.

Node.js

const fs = require([1]);

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

A'fs'

Bfilesystem

C"fileSystem"

Dfs

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the module name.

Using incorrect module names.

In Node.js, to use a built-in module like fs, you must require it by its name as a string.

2fill in blank

medium

Complete the code to export a function from a module.

Node.js

module.exports = [1];

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

Afunction readFile() {}

BreadFile()

C"readFile"

DreadFile

Attempts:

3 left

💡 Hint

Common Mistakes

Exporting a function call instead of the function.

Exporting the function name as a string.

To export a function, assign the function itself (not a call or string) to module.exports.

3fill in blank

hard

Fix the error in importing a custom module.

Node.js

const utils = require([1]);

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

A'utils.js'

B'../utils'

C'utils'

D'./utils'

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the relative path prefix.

Including the file extension when not needed.

When importing a local module, you must use a relative path starting with ./ or ../.

4fill in blank

hard

Fill both blanks to create a module that exports an object with two functions.

Node.js

module.exports = { [1]: function() {}, [2]: () => {} };

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

Astart

Bstop

Crun

Dpause

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid identifiers as keys.

Forgetting commas between object properties.

We export an object with keys naming the functions. Here, start and stop are function names.

5fill in blank

hard

Fill all three blanks to import a module, call a function, and log the result.

Node.js

const [1] = require('[2]');
const result = [3].calculate();
console.log(result);

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

AmathUtils

Bmath-utils

Cutils

Dutils.js

Attempts:

3 left

💡 Hint

Common Mistakes

Using file extension in require path.

Mismatching variable and module names.

We import the module as mathUtils from 'math-utils', then call mathUtils.calculate().

Practice

1. Why do Node.js developers use modules in their code?

easy

A. To write code without functions

B. To make the code run faster

C. To avoid using variables

D. To organize code into smaller, manageable parts

Solution

1. Step 1: Understand the purpose of modules

   Modules help split code into smaller files, making it easier to manage.

2. Step 2: Compare options with module benefits

   Only organizing code into smaller parts matches the main reason for using modules.

3. Final Answer:

   To organize code into smaller, manageable parts -> Option D

4. Quick Check:

   Modules = Organize code [OK]

Hint: Modules help split code for easier management [OK]

Common Mistakes:

• Thinking modules make code run faster
• Believing modules remove the need for variables
• Assuming modules eliminate functions

2. Which of the following is the correct way to import a module named mathUtils in Node.js?

easy

A. const mathUtils = require('mathUtils');

B. include('mathUtils');

C. import mathUtils from 'mathUtils';

D. use mathUtils;

Solution

1. Step 1: Recall Node.js module import syntax

   Node.js uses require() to import modules in CommonJS style.

2. Step 2: Match options with correct syntax

   Only const mathUtils = require('mathUtils'); is valid Node.js syntax.

3. Final Answer:

   const mathUtils = require('mathUtils'); -> Option A

4. Quick Check:

   Node.js imports = require() [OK]

Hint: Use require() to import modules in Node.js [OK]

Common Mistakes:

• Using import without setup (not default in Node.js)
• Using include() which is not valid in Node.js
• Using use keyword which doesn't exist

3. Consider this Node.js code snippet:

const greet = require('./greet');
console.log(greet('Anna'));

What is the expected output if greet.js exports a function that returns `Hello, ${name}!`?

medium

A. Hello, Anna!

B. greet is not defined

C. undefined

D. SyntaxError

Solution

1. Step 1: Understand module import and function call

   The greet module exports a function that returns a greeting string.

2. Step 2: Predict console output

   Calling greet('Anna') returns Hello, Anna!, which is logged.

3. Final Answer:

   Hello, Anna! -> Option A

4. Quick Check:

   Function call output = Hello, Anna! [OK]

Hint: Imported functions return expected results when called [OK]

Common Mistakes:

• Assuming greet is undefined without import
• Expecting undefined if export is missing
• Confusing syntax errors with runtime output

4. What is wrong with this Node.js code snippet?

const utils = require('./utils');
console.log(utils.add(2, 3));

// utils.js content:
// module.exports = {
//   add: (a, b) => a + b
// }

medium

A. The require path should include file extension

B. The module.exports syntax is incorrect

C. No error, code works correctly

D. The add function is not exported properly

Solution

1. Step 1: Check require path usage

   Node.js allows requiring files without extension if .js is default.

2. Step 2: Verify module.exports and function export

   The add function is correctly exported as an object property.

3. Step 3: Confirm usage in main file

   Calling utils.add(2, 3) is valid and returns 5.

4. Final Answer:

   No error, code works correctly -> Option C

5. Quick Check:

   Correct export and import = works [OK]

Hint: Default .js extension is optional in require [OK]

Common Mistakes:

• Thinking file extension is mandatory in require
• Believing module.exports syntax is wrong
• Assuming function is not exported properly

5. You have two modules: math.js exports functions add and multiply, and app.js imports them. How does using modules help when your project grows larger?

hard

A. Modules automatically speed up your code execution

B. Modules let you reuse code and avoid repeating functions in many files

C. Modules prevent any bugs from happening

D. Modules force all code to be in one file

Solution

1. Step 1: Understand code reuse with modules

   Modules allow sharing functions like add and multiply across files without rewriting.

2. Step 2: Evaluate other options

   Modules do not automatically speed up code or prevent bugs, nor do they force single-file code.

3. Final Answer:

   Modules let you reuse code and avoid repeating functions in many files -> Option B

4. Quick Check:

   Modules = Code reuse and organization [OK]

Hint: Modules help reuse code across files [OK]

Common Mistakes:

• Thinking modules speed up code automatically
• Believing modules prevent bugs completely
• Assuming modules combine all code into one file