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Summary - npm

Combine install, scripts and semver to set up a project.

Summary - npm

In this group you learned the core tools of npm: installing packages with npm install, defining commands with scripts, separating development packages with devDependencies, version ranges with semver and publishing with npm publish.

You can combine these five tools to set up a real project. For example, you can read a package.json and print the name, version and script count. This is the basic way to inspect a package's structure. Now you will combine all pieces in one piece of code.

Practice Print name@version and the script count

Define a string named content with the value {"name":"my-lib","version":"1.0.0","scripts":{"start":"node index.js","test":"jest"}}. Parse it into an object with JSON.parse. First print pkg.name + "@" + pkg.version, then print Object.keys(pkg.scripts).length on a separate line, both with console.log.

Starter code

index.js
// Define the package.json content (name, version, scripts)
// Parse it into an object with JSON.parse
// Print name@version, then the scripts count
// write here

Sample solution

index.js
const content = '{"name":"my-lib","version":"1.0.0","scripts":{"start":"node index.js","test":"jest"}}';
const pkg = JSON.parse(content);
console.log(pkg.name + "@" + pkg.version);
console.log(Object.keys(pkg.scripts).length);

Expected output

my-lib@1.0.0
2

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Match each tool to its role

Term Meaning
npm install Installs packages
scripts Defines commands
devDependencies Dev packages
semver Version range

2 What does scripts.test do in package.json?

index.js
scripts.test
  • Deletes test files
  • Installs the test package
  • The script that npm test runs Correct answer
  • Logs during tests

Explanation: The scripts.test field defines the npm test command.

3 Complete the tilde range

Question 
"____1.2.3"
Answer 
"~1.2.3"

Explanation: ~1.2.3 allows only patch-level updates.

All lessons in Intermediate

1 Events

  1. EventEmitter
  2. on and emit
  3. once
  4. removeListener
  5. error event
  6. Summary - Events

2 Streams

  1. What are streams?
  2. Readable stream
  3. Writable stream
  4. pipe
  5. Transform stream
  6. Summary - Streams

3 HTTP server

  1. http.createServer
  2. Request and response
  3. Routing
  4. JSON response
  5. Query string
  6. Summary - HTTP server

4 Project: Helper library

  1. Module design
  2. String helpers
  3. Number helpers
  4. Date helpers
  5. Putting it together

5 Express basics

  1. What is Express?
  2. express()
  3. app.get
  4. app.post
  5. app.listen
  6. Summary - Express basics

6 Middleware

  1. What is middleware?
  2. app.use
  3. Router middleware
  4. Error middleware
  5. Body parser
  6. Summary - Middleware

7 Routing

  1. Route parameters
  2. Query parameters
  3. express.Router
  4. Route groups
  5. Method chaining
  6. Summary - Routing

8 Project: Quiz app

  1. Quiz model
  2. Adding questions
  3. Running the quiz
  4. Score calculation
  5. Putting it together

9 Async patterns

  1. Async iteration
  2. Async generators
  3. Concurrency limit
  4. Retry pattern
  5. Debounce and throttle
  6. Summary - Async patterns

10 Buffer and binary

  1. What is Buffer?
  2. Buffer.from
  3. Buffer.concat
  4. toString and encoding
  5. Buffer slice
  6. Summary - Buffer

11 Process and CLI

  1. process.argv
  2. process.env
  3. process.exit
  4. process.stdin/stdout
  5. Child process
  6. Summary - Process

12 Project: Library API

  1. Model design
  2. Express app
  3. CRUD routes
  4. Middleware
  5. Putting it together

13 npm and packages

  1. npm install
  2. package.json scripts
  3. devDependencies
  4. Semver
  5. npm publish
  6. Summary - npm

14 Error handling

  1. The Error class
  2. try/catch
  3. Custom errors
  4. Error middleware
  5. Unhandled rejection
  6. Summary - Error handling

15 Testing basics

  1. node:test
  2. assert
  3. describe and it
  4. Before and after
  5. Mock
  6. Summary - Testing basics

16 Debugging

  1. node inspect
  2. Chrome DevTools
  3. console methods
  4. util.inspect
  5. Source maps
  6. Summary - Debugging

17 Date and time

  1. The Date object
  2. Date methods
  3. Intl.DateTimeFormat
  4. performance.now
  5. setTimeout and setInterval
  6. Summary - Date and time

18 Crypto

  1. crypto module
  2. createHash
  3. randomBytes
  4. HMAC
  5. AES
  6. Summary - Crypto

19 URL and query string

  1. URL object
  2. URLSearchParams
  3. URL properties
  4. URL.resolve
  5. querystring
  6. Summary - URL and query string

20 Intermediate final

  1. Project design
  2. Express API
  3. fs persistence
  4. Middleware
  5. Putting it together