Web 322 - Express Basics
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Questions and Answers

Which command is used to install a third-party package locally in a Node.js project?

  • npm init
  • npm remove
  • npm install -g
  • npm install (correct)

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

  • Stores project dependencies and configuration. (correct)
  • Contains the code for the main application logic.
  • Defines database connections and settings.
  • Holds the user interface design elements.

    • Which of the following is NOT a framework mentioned as an alternative to Express?

  • React (correct)
  • Adonis.js
  • Sails.js
  • Koa

    • What is the main difference between a framework and a library?

    <p>Frameworks control the flow of the application, while libraries are called upon demand. (A)</p> Signup and view all the answers

    Which of the following is a key feature of Express middleware?

    <p>Intercepts incoming requests and performs actions before reaching the route handler. (B)</p> Signup and view all the answers

    How do you run a JavaScript program using the Node.js command-line interpreter?

    <p>node [filename] (C)</p> Signup and view all the answers

    What is the purpose of the npm init command?

    <p>To create a new Node.js project. (C)</p> Signup and view all the answers

    What is the advantage of using Express compared to vanilla Node.js for building web applications?

    <p>Express provides a more structured and organized way to handle requests and routes. (D)</p> Signup and view all the answers

    What does the app.locals object in Express allow you to do?

    <p>Attach local variables to the application (C)</p> Signup and view all the answers

    Which method would you use to redirect a browser to a different page in Express?

    <p>redirect() (A)</p> Signup and view all the answers

    What is the primary purpose of middleware functions in Express?

    <p>To access the request and response objects (D)</p> Signup and view all the answers

    In Express, what does the use() method accomplish?

    <p>It attaches middleware to your application (A)</p> Signup and view all the answers

    To handle HTTP POST requests in Express, which method would you use?

    <p>post() (D)</p> Signup and view all the answers

    Which command is utilized to send a JSON object back to the client in Express?

    <p>json() (A)</p> Signup and view all the answers

    What kind of resources should be specified in a folder for static serving in Express?

    <p>Static resources like CSS or image files (A)</p> Signup and view all the answers

    What does the params property of the request object contain?

    <p>Dynamically read variables from the URL (B)</p> Signup and view all the answers

    What is the primary function of Node.js?

    <p>Creating dynamic web applications (B)</p> Signup and view all the answers

    Which of the following correctly describes a package in Node.js?

    <p>A collection of one or more modules grouped together (D)</p> Signup and view all the answers

    What distinguishes third-party modules from local modules in Node.js?

    <p>Third-party modules need to be installed using a package manager. (B)</p> Signup and view all the answers

    Which module would you use to work with file input/output in Node.js?

    <p>fs (A)</p> Signup and view all the answers

    What does NPM stand for in the context of Node.js?

    <p>Node Package Manager (C)</p> Signup and view all the answers

    Which of the following commands would you use to create a package.json file?

    <p>npm init (B)</p> Signup and view all the answers

    What type of modules are automatically loaded when Node.js starts?

    <p>Core modules (D)</p> Signup and view all the answers

    What information does the 'os' module provide in Node.js?

    <p>Information about the operating system (C)</p> Signup and view all the answers

    Flashcards

    Middleware Functions

    Functions that have access to request and response objects in Express.

    HTTP Requests

    Requests made by clients to interact with server resources in Express.

    Routes in Express

    Define specific URLs on a server that handle client requests.

    app.locals

    Allows attaching local variables to the application in Express.

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    app.listen()

    Starts the server and begins listening for incoming requests.

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    req.body

    Contains data submitted from client requests in Express.

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    res.cookie()

    Sets a cookie in the response that gets sent to the browser.

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    Serving Static Files

    Serving unchanging resources like CSS or image files from a specified directory.

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    Node.js

    A JavaScript runtime for building server-side applications.

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    Modules

    Reusable code in Node.js, encapsulated in files.

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    Core Modules

    Built-in Node.js modules loaded automatically.

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    3rd Party Modules

    External modules created by others, installable via NPM.

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    Local Modules

    Modules created by you for your specific application.

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    NPM

    Node Package Manager, used to install and manage packages.

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    package.json

    A manifest file that describes your Node.js project.

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    Packages

    Collections of modules bundled together for reusable functionality.

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    npm init

    Command to create a package.json file for a project.

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    Local Package Installation

    Installing a package locally makes it accessible only in the project folder.

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    npm install

    Command to install third-party packages in Node.js.

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    Remove Package Command

    Use npm remove to delete a package and update package.json.

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    Express Framework

    A popular Node.js framework for building web applications and APIs.

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    Framework vs Library

    Framework controls the app's flow; a library requires your direction.

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    Middleware in Express

    Functions that process HTTP requests and responses in Express applications.

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    Study Notes

    Web 322 - Express Basics

    • This lecture covers Express, a popular and flexible Node.js framework for building web applications and APIs.

    Node.js Review

    • Node.js is a JavaScript runtime environment.
    • Node.js allows building web applications and APIs.
    • Alternatives to Node.js exist.
    • Advantages of Node.js are discussed in the slides.

    Modules vs Libraries

    • Modules are libraries in Node.js; a set of functions for inclusion in an application.
    • Examples of modules include Circle.js, Rectangle.js, and Square.js.
    • Packages group modules or libraries together.
    • Node.js uses a package manager to find and install packages (like NPM).

    Modules in Node.js

    • Modules organize functionality into files (simple or complex).
    • Modules are reusable throughout applications.
    • Each module has its own context and doesn't interfere with other modules, preventing scope pollution.
    • Core modules load automatically when Node.js starts.
    • Third-party modules need installation (like NPM).
    • Local modules are created by developers for specific application functionalities.

    Core Node.js Modules

    • The http and https modules create HTTP servers.
    • The fs module handles file input/output (I/O).
    • The path module manages file paths.
    • The os module provides information about the operating system.

    What is NPM?

    • NPM (Node Package Manager) is the official package manager for Node.js.
    • It's a command-line client and an NPM registry (online database of packages).
    • NPM is bundled and installed automatically with Node.js.

    NPM & Packages

    • Packages are managed through NPM.
    • The diagram shows how local projects, core packages, and dependencies are managed via NPM.

    Basic NPM Commands

    • npm init or npm init -y creates a package.json file (project manifest).
    • npm install <package name> or npm i <package name> installs a 3rd-party package locally.
    • npm remove <package name> removes a package.

    Node Commands

    • Execute JavaScript programs with node <entry-point filename>.
    • The .js extension can be omitted.

    Package.json File

    • package.json is central to the Node.js ecosystem, like a manifest.
    • It manages applications, modules, packages, and other metadata.

    What is Express?

    • Express is a popular and flexible Node.js framework.
    • It's designed for building web applications and APIs.
    • It's a standard server framework for Node.js.
    • Express simplifies handling requests and routes.

    Alternative Frameworks to Express

    • Vanilla Node.js, Adonis.js, Koa, and Sails.js are alternatives to Express.

    Frameworks vs Libraries

    • Both frameworks and libraries contain code written by others, often used to address common problems.
    • Libraries allow you to control the application flow, choosing when and where to call functions.
    • Frameworks dictate the application flow, providing places to plug in custom code.

    Middleware

    • Middleware functions in Express handle requests until a response is sent to the browser.
    • Express middleware functions have access to the request and response objects.

    What Can We Do With Express?

    • Express handles HTTP requests.
    • It supports handling responses on specific URLs.
    • It supports various templating engines.

    Routing

    • Routing in Express handles URLs mapped to client access.
    • A route is a path on a website handling requests.

    Three Core Objects of Express (app)

    • The app object in Express provides functionalities like attaching local variables (locals), starting the listening process (listen()) and adding middlewares (use()).

    Three Core Objects of Express (req)

    • The req object (request) contains information like the request body and cookies.
    • It includes dynamically read values from URLs, query strings and headers.

    Three Core Objects of Express (res)

    • The res object (response) manages server responses to requests.
    • It enables setting cookies, handling file downloads, ending responses, sending JSON objects and redirects.

    Serving Static Files

    • Static files (like CSS & images) aren't dynamic.
    • Use the app.use(express.static("static")); method. Static resources can load from folders without needing to add them into the URL.

    Error Handling

    • Middleware facilitates error handling.
    • Code includes error parameters like handleClientError(err, req, res, next).
    • next() transfers control to the next error handler; errors can be logged.

    Processing Form Data

    • body-parser processes (text-based e.g. forms) submissions.
    • multer or express-fileupload handles multi-part submissions (text & files).

    Demo of Express

    • A demo illustrating Express usage is available.

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    Related Documents

    WEB 322 Express Basics Lecture

    Description

    This quiz covers the fundamentals of Express, a key Node.js framework that facilitates the development of web applications and APIs. You'll also review Node.js as a JavaScript runtime and learn about the distinctions between modules and libraries. Enhance your understanding of creating efficient web applications using these essential tools.

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