Node.js Overview and Installation
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Node.js is a server-side runtime environment built on Google Chrome's JavaScript Engine (V8 Engine).

True

Node.js is a programming language like Python, Java, or C/C++.

False

Node.js is a cross-platform runtime environment, meaning it can run on various operating systems like Windows, Linux, Unix, macOS, and more.

True

Node.js executes JavaScript code within a web browser.

<p>False</p> Signup and view all the answers

Node.js converts JavaScript code into machine code, similar to the Java Virtual Machine.

<p>True</p> Signup and view all the answers

Node.js is not widely used by developers.

<p>False</p> Signup and view all the answers

Node.js primarily aims to develop I/O-intensive web applications like video streaming sites and single-page applications.

<p>True</p> Signup and view all the answers

Node.js does not allow using JavaScript for backend development.

<p>False</p> Signup and view all the answers

Node.js utilizes a single thread for asynchronous execution of tasks, making it significantly faster than multi-threaded applications.

<p>True</p> Signup and view all the answers

Node.js is used to build a wide range of applications, including command-line tools, web applications, real-time chat apps, and REST APIs.

<p>True</p> Signup and view all the answers

To install and set up an environment for Node.js, you need only a text editor.

<p>False</p> Signup and view all the answers

The source files for Node.js programs typically have the extension '.js'.

<p>True</p> Signup and view all the answers

The source code in Node.js files is written directly in machine code.

<p>False</p> Signup and view all the answers

To use Node.js, you must use the 'node' command from the Node.js command prompt to run a file named 'example1.js'.

<p>True</p> Signup and view all the answers

What are the three essential parts of a Node.js web application?

<p>Read request and return response</p> Signup and view all the answers

What directive is used to import a Node.js module?

<p>require</p> Signup and view all the answers

What does 'http.createServer()' do in Node.js?

<p>Creates a server instance that can listen for incoming HTTP requests.</p> Signup and view all the answers

What is the purpose of the 'listen' method in Node.js when working with a server?

<p>Binds the server to a specific port and begins listening for requests.</p> Signup and view all the answers

What does 'response.writeHead(200, {'Content-Type': 'text/plain'});' achieve within the server response in Node.js?

<p>This sets the response header with a status code of 200 (success) and indicates that the response content is plain text.</p> Signup and view all the answers

What is the role of 'response.end('Hello World ');' in a Node.js server response?

<p>This sends the actual response content, in this case, the string 'Hello World' to the client making the request.</p> Signup and view all the answers

What command is commonly used to start a Node.js server from the command prompt?

<p>node console.js</p> Signup and view all the answers

The 'console' module in Node.js provides debugging capabilities similar to the JavaScript console found in web browsers.

<p>True</p> Signup and view all the answers

What are the three console methods used in Node.js to write to a stream?

<p>console.log()</p> Signup and view all the answers

The 'console.log()' function prints messages on the console, serving as a simple method for displaying information.

<p>True</p> Signup and view all the answers

The 'console.warn()' method is used to display error messages on the console.

<p>False</p> Signup and view all the answers

'console.error()' is designed for outputting error messages, providing developers with more significant visual indicators of problems.

<p>True</p> Signup and view all the answers

What does REPL stand for in terms of Node.js?

<p>Read Eval Print Loop</p> Signup and view all the answers

The Node.js environment is bundled with a REPL environment, which provides a way to interact with Node.js in an interactive console-like manner.

<p>True</p> Signup and view all the answers

What are the four primary functions within the REPL environment?

<p>Loop</p> Signup and view all the answers

In the REPL environment, the 'Read' phase involves parsing user input and storing it in memory.

<p>True</p> Signup and view all the answers

'Eval' in the REPL determines the meaning of the input and executes the JavaScript code.

<p>True</p> Signup and view all the answers

The 'Print' phase in the REPL displays the results of the executed JavaScript code to the user.

<p>True</p> Signup and view all the answers

The 'Loop' function in the REPL is a single-time process that ends after the first input.

<p>False</p> Signup and view all the answers

You can start the REPL by simply typing 'node' in the command prompt.

<p>True</p> Signup and view all the answers

REPL allows you to evaluate mathematical expressions directly.

<p>True</p> Signup and view all the answers

The 'underscore' character (_, a special character in REPL), can be used to access the previous result in REPL.

<p>True</p> Signup and view all the answers

What combination of keys can be used to exit the Node.js REPL?

<p>Ctrl + C twice</p> Signup and view all the answers

Variables in the REPL are used to store values and enable later access.

<p>True</p> Signup and view all the answers

Ctrl + C, when pressed once in the REPL, completely terminates the REPL environment.

<p>False</p> Signup and view all the answers

Ctrl + D is another method to terminate the REPL environment.

<p>True</p> Signup and view all the answers

The 'up/down' arrow keys are used to view the history of commands executed within the REPL.

<p>True</p> Signup and view all the answers

The 'tab' key in the REPL provides a list of possible command options.

<p>True</p> Signup and view all the answers

The '.help' command in the REPL lists all available commands within the Node.js environment.

<p>False</p> Signup and view all the answers

The '.break' command exits from multi-line expressions within the REPL.

<p>True</p> Signup and view all the answers

The '.clear' command is similar to the '.break' command in its functionality.

<p>True</p> Signup and view all the answers

The '.save filename' command saves the current REPL session to a file.

<p>True</p> Signup and view all the answers

The '.load filename' command loads the contents of a previously saved REPL file into the текущей REPL session.

<p>True</p> Signup and view all the answers

The Node Package Manager (npm) provides online repositories for Node.js packages/modules, which are searchable on the website 'search.nodejs.org'.

<p>True</p> Signup and view all the answers

Npm provides a command-line utility to install packages, manage versions, and handle dependencies.

<p>True</p> Signup and view all the answers

The npm command is only available in Node.js versions later than v0.6.3.

<p>False</p> Signup and view all the answers

To check the version of npm, you can open the command prompt and type 'npm version'.

<p>True</p> Signup and view all the answers

What is the basic command syntax for installing a Node.js module using npm?

<p>npm install &lt;Module Name&gt;</p> Signup and view all the answers

The 'express' module is a popular Node.js web framework that can be installed using the command 'npm install express'.

<p>True</p> Signup and view all the answers

The 'require' function is used to import and use npm modules within your JavaScript code.

<p>True</p> Signup and view all the answers

By default, npm installs dependency packages in a 'global' mode, making them universally accessible across projects.

<p>False</p> Signup and view all the answers

The 'node_modules' directory is created within the current project directory when you use npm to install dependencies.

<p>True</p> Signup and view all the answers

The command 'npm ls' is used to list all installed modules within your project.

<p>True</p> Signup and view all the answers

Globally installed packages are stored in the system directory, making them available to all projects on your system.

<p>True</p> Signup and view all the answers

The command 'npm install express -g' installs express globally, making it available for all projects on the system.

<p>True</p> Signup and view all the answers

To uninstall a Node.js module, you can use the command'npm uninstall <Module Name>'.

<p>True</p> Signup and view all the answers

The command 'npm Is' can be used to verify if a module has been successfully uninstalled.

<p>True</p> Signup and view all the answers

The option --version or -v is used to display the version of the Node.js interpreter.

<p>True</p> Signup and view all the answers

The --help or -h option is used to display help information for various Node.js commands.

<p>True</p> Signup and view all the answers

The --eval option or -e is designed to evaluate JavaScript code directly.

<p>True</p> Signup and view all the answers

The --print option in Node.js executes the JavaScript code and displays the result on the console.

<p>True</p> Signup and view all the answers

The --check option or -c performs a syntax check on a provided JavaScript without actually executing it.

<p>True</p> Signup and view all the answers

The --interactive option or -i launches the Node.js REPL environment.

<p>True</p> Signup and view all the answers

Global objects in Node.js are accessible only within the specific module where they are defined.

<p>False</p> Signup and view all the answers

You can use these global objects directly without the need to explicitly import or include them.

<p>True</p> Signup and view all the answers

Global objects include modules, functions, strings, and objects, providing a broad range of capabilities.

<p>True</p> Signup and view all the answers

The _dirname global object is used to identify the current working directory where the code is executed.

<p>True</p> Signup and view all the answers

The _filename global object holds the complete file name, including its file extension and path, of the executed JavaScript code.

<p>True</p> Signup and view all the answers

Node.js applications may encounter four distinct types of errors during execution.

<p>True</p> Signup and view all the answers

Standard JavaScript errors typically include EvalError, SyntaxError, RangeError, ReferenceError, TypeError, and URIError, among others.

<p>True</p> Signup and view all the answers

System errors occur when Node.js encounters a problem related to underlying system operations, such as file access, networking, or hardware issues.

<p>True</p> Signup and view all the answers

'User-specified errors' are usually created automatically by Node.js to identify a specific issue in the application logic.

<p>False</p> Signup and view all the answers

Assertion errors occur when a condition that is expected to be true within the code is found to be false.

<p>True</p> Signup and view all the answers

Streams are a mechanism that enables data to be written to a specific destination, but does not allow for reading data from a source.

<p>False</p> Signup and view all the answers

What are the four main types of streams in Node.js?

<p>Readable</p> Signup and view all the answers

Readable streams are designed for writing data to a destination.

<p>False</p> Signup and view all the answers

'Writable' streams are used for reading data, while 'Duplex' streams handle both reading and writing.

<p>False</p> Signup and view all the answers

Transform streams are a type of 'Duplex' stream where the output is calculated based on the input data.

<p>True</p> Signup and view all the answers

In Node.js streams, the 'data' event is triggered when data is available to be read.

<p>True</p> Signup and view all the answers

The end event signals the end of data transmission in a stream, indicating that there is no more data available for reading.

<p>True</p> Signup and view all the answers

The error event is triggered if any errors occur while reading or writing data to a Node.js stream.

<p>True</p> Signup and view all the answers

The finish is fired when all data has been transferred.

<p>True</p> Signup and view all the answers

You must use 'fs.createReadStream()' to read a file in Node.js.

<p>True</p> Signup and view all the answers

When reading from a stream, you can handle events like 'data', 'end', and 'error' by using the '.on' function in Node.js streams.

<p>True</p> Signup and view all the answers

You create a file named 'input.txt' to read from in Node.js.

<p>True</p> Signup and view all the answers

The 'fs.createWriteStream()' function is used to create a write stream in Node.js.

<p>True</p> Signup and view all the answers

Node.js uses a mechanism called piping. This allows you to use the output from one stream as the input to another stream.

<p>True</p> Signup and view all the answers

The command 'readerStream.pipe(writerStream)' is used to combine the processes of reading and writing streams.

<p>True</p> Signup and view all the answers

Study Notes

Node.js Overview

  • Node.js is a server-side runtime environment built on Google Chrome's JavaScript Engine (V8 Engine).
  • It's not a programming language, but a runtime environment for executing JavaScript code outside a web browser.
  • Node.js is cross-platform (Windows, Linux, Unix, macOS).
  • It's open-source and widely used by many developers.
  • Node.js converts JavaScript code to machine code.
  • It's used to create I/O-intensive web applications such as video streaming sites and single-page applications.
  • Node.js enables JavaScript use as a backend programming language for all parts of an application (both front-end and back-end).
  • Asynchronous execution within a single thread (using async/await) enhances application speed.
  • Node.js runtime environment is suitable for many types of application development including command-line utilities, web applications, real-time chat applications, and REST APIs.

Node.js Installation

  • To use Node.js, you need a text editor and a Node.js binary installable.
  • Node.js programs have the ".js" file extension.
  • The source code within the .js files is written in JavaScript, and interpreted & executed by the Node.js interpreter.
  • Download Node.js from the official website (https://nodejs.org/en/).

Node.js First Example

  • A Node.js web application has three parts:
    • Import required modules (using the require directive).
    • Create a server (similar to Apache HTTP).
    • Read client requests and send responses.

Steps to Create a Node.js Web Application

  • Load the http module.
  • Create an HTTP server.
  • Define handling of client requests by providing a request and response function.
  • Start the server on a specific port (e.g., port 8081).
  • The server responds to requests with "Hello World".

To Start the Server

  • Open Node.js command prompt.
  • Execute the console.js file.
  • The server runs on http://127.0.0.1:8081/.
  • Access it by opening this address in a web browser to see the result.

Node.js Console

  • Node.js provides a console for debugging.
  • It has three methods: console.log(), console.error(), and console.warn().
  • console.log() displays messages on the console.

Node.js REPL

  • REPL (Read-Eval-Print-Loop) is an interactive command line shell for Node.js.
  • It allows users to enter commands and receive immediate responses.
  • ctrl + c twice exits the REPL.
  • Variables can be used to store and retrieve values.
  • Multiline expressions can be used.
  • Use _ to refer to the last result.

Node.js Package Manager (npm)

  • npm (Node Package Manager) is a package manager for Node.js.
  • npm provides online repositories for node.js packages/modules (searchable).
  • It helps install and manage dependencies.
  • npm comes bundled with Node.js after version 0.6.3.
  • Check npm version by typing at command prompt: npm version

Installing Node.js Modules Using npm

  • Use npm install <module name> to install a module.
  • npm install express installs the express module.

Global vs. Local Installation

  • Globally installed modules are stored in the system directory.
  • Locally installed modules are stored in the Node application directory.
  • Use npm install <module name> -g to install a package globally.
  • Use npm uninstall express to uninstall a module.
  • Use npm ls to list all locally installed modules.

Node.js Command-Line Options

  • Node.js provides various command-line options:
    • v or --version to get the Node version.
    • -h or --help to show command-line options.
    • -e or --eval "script" evaluates JavaScript code.
    • -p or --print "script" evaluates and prints the result
    • -c or --check performs syntax checking.
    • -i or --interactive opens the REPL.

Node.js Global Objects

  • Node.js has built-in global objects available in all modules.
  • For example: dirname, filename, console, process.

Node.js Errors

  • Node.js applications can encounter various errors. Some examples are standard JS errors, system errors (hardware/network problems), and assertion errors (logic failures).

Node.js Streams

  • Node.js facilitates reading and writing data between sources and destinations using streams.

  • Types of streams include:

    • Readable (reading), Writable (writing), Duplex (read write), Transform (computing based on input)

  • Common stream events include: data, end, error and complete

  • Data handling in streams can be improved by using asynchronous callbacks to avoid blocking

Node.js Piping Streams

  • Piping a stream allows using one stream's output as another's input.

Callbacks

  • A callback is an asynchronous equivalent to a function, used in Node.js for non-blocking operations.
  • Callbacks are particularly useful for lengthy operations or when dealing with external resources (like file systems) to prevent blocking.
  • Node.js often uses callbacks, for example setTimeout.
  • Synchronous operations (e.g., using readFileSync) block subsequent execution. Asynchronous callbacks prevent such blocking.

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Node.js Tutorial PDF

Description

This quiz provides an overview of Node.js, a popular server-side runtime environment for executing JavaScript outside the browser. It covers its features, usage in web application development, and the installation process needed to get started with Node.js. Test your knowledge on the fundamentals of Node.js and enhance your programming skills.

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