The code below shows how we import a module by name, using the Express framework as an example. First we invoke the require() function, specifying the name of the module as a string (‘express’), and calling the returned object to create an Express application. We can then access the properties and functions of the application object. A module is a JavaScript library/file that you can import into other code using Node’s require() function. Express itself is a module, as are the middleware and database libraries that we use in our Express applications.

The event loop is what allows everything to work together. Node loops through the phases, keeping track of our unfinished asynchronous tasks. The event loop keeps looping and checking on our async operations. Asynchronous code involves the JavaScript engine in our internet browser that we mentioned earlier. JavaScript can hand off tasks to the web API that is part of the web browser’s engine.Once the tasks complete in the browser, the result is pushed to the call stack as a callback. A callback is a set of instructions in the form of a function.

Package management

Back in 1995, JavaScript was created as a client-side scripting language. In building a website, you can use HTML in designing and CSS to make it more attractive. The function recursively calls a function for each descendant node of
rootNode (including the root itself). For example,
attempting to add children to a node type that cannot have children will throw an
exception. In addition, every kind of DOM node is represented by an interface based on
Node. These include Attr, CharacterData
(which Text, Comment, CDATASection and
ProcessingInstruction are all based on), and DocumentType.

This need is why JavaScript now has the capabilities to handle backend responsibilities and is considered a full-stack language. When JavaScript was first created, it was something you could only run in the browser. This meant the backend was handled by other languages like Python or Ruby on Rails. You know the basics of Node.js, its fundamental tools, and how to start a Node.js file. The next steps are to master Node.js modules, the HTTP Modules, File system, and NPM dependencies. This particular method will fire when an event is emitted.

Node.js Tutorial

V8 is Google’s open source high-performance JavaScript and WebAssembly engine, written in C++. It implements ECMAScript and WebAssembly, and runs on Windows 7 or later, macOS 10.12+, and Linux systems that use x64, IA-32, ARM, or MIPS processors. V8 can run standalone, or can be embedded into any C++ application.

The value of Node.js comes from building user interactivity by integrating it with a backend database. That can happen using Express.js, but it’ll have to wait for another time. Developers can leverage these modules to accelerate development and enhance application functionality. Running commands in the REPL is great for demo purposes, but Node wouldn’t be beneficial if that were the only place you could interact with the Node runtime.

Examples of Node.js Use

Express is a popular unopinionated web framework, written in JavaScript and hosted within the Node.js runtime environment. This module explains some of the key benefits of the framework, how to set up your development environment and how to perform common web development and deployment tasks. Node.js provides a runtime environment outside of the browser. This makes it possible to build back-end applications using the same JavaScript programming language you may be familiar with. As the Node.js API is subject to breaking changes at a binary level, modules have to be built and shipped against specific Node.js versions to work properly. To address the issue, third parties have introduced open-sourced С/С++ wrappers on top of the API that partially alleviate the problem.

However, GitHub’s Node Modules Wiki is much more complete and a good resource. When you actually run npm init to initialize a directory for a new project, a script will ask you some questions. The default values npm suggests for you will include 1.0.0 as a version number and an entry point of index.js. Finally, we call the server function using the listen method and specifying the port number, and then writing an entry to console.log. You’ve created a straightforward web application and served it with NodeJS. And for the browser, the parts of the outside world it allows you to see (interact with) with are the Window object and, subsequently, the document object, or DOM.

Window vs Global object

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The database itself can be installed locally or on a cloud server. In your Express code you require the driver, connect to the database, and then perform create, read, update, and delete (CRUD) operations. The example below (from the Express documentation) shows how you can find “mammal” https://wizardsdev.com/en/vacancy/nodejs-developer/ records using MongoDB. You can call static() multiple times to serve multiple directories. If a file cannot be found by one middleware function then it will be passed on to the subsequent middleware (the order that middleware is called is based on your declaration order).

“Single threaded” means that all requests to the server are run on the same thread (rather than being spawned off into separate processes). But isn’t JavaScript slow / bad / evil / spawn-of-the-devil? JavaScript has some weird oddities, but with “the good parts” there’s a very powerful language there, and in any case, JavaScript is THE language on the client (browser).

• We use the fs module and the writeFile method to do this.
• And the language is so darn flexible that you really aren’t coding JavaScript, you are coding Step or jQuery — more than any other language, in JavaScript, the libraries define the experience.
• Node.js runs single-threaded, non-blocking, asynchronous programming, which
  is very memory efficient.
• There is a special routing method, app.all(), which will be called in response to any HTTP method.

Instead of spending time and money core operations, you are meaninglessly exerting effort to the wrong side of the business. This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution.