Additional Terminology

If you are new to Node.js, then you have probably seen some terms that you are not entirely sure what they mean in this context. That is why we wanted to explain a few of them, as they will also appear in this tutorial. We already mentioned what runtime environment and modules are, but there are a few more we want to mention.

• Web Application - That is what we will be building with Node.js. A web application is a piece of software that runs on a web server and interacts with inputs from users, either via a browser or a client-side application;
• Application Instance - This refers to a singular and independent instance of Node.js running on your server. Express.js can also have application instances, for example, and such instances are where the application itself runs;
• Call - A call in the context of Node.js involves invoking a function within the application, which can be done synchronously or asynchronously. It differs from an HTTP request as it involves functions solely within the application. It executes code;
• HTTP Request - This is not a term specific to Node.js or programming but is often seen in such contexts. It describes a message sent to a web server by a client (browser or some application). The message requests a specific resource or action, to which the web server responds. For example, when you open an image online, your browser sends an HTTP request to the server the image is on, and the server returns the image. It then opens in your browser. There are several methods via which your browser or application can send requests to the server;
  • GET - Retrieve data or resources from the server;
  • POST - Submit data to the server for processing or storage;
  • PUT - Update or replace an existing resource on the server;
  • DELETE - Request the removal of a resource on the server;
  • PATCH - Apply partial modifications to a resource;
  • HEAD - Similar to GET but requests only the headers, not the actual content;
  • OPTIONS - Request information about the communication options available for a resource;
• Route - Routes are used to map and direct incoming HTTP requests to specific functions or handlers, which will then process those requests. An application can’t function without routes, as they dictate how the application itself responds to various requests;
• URL Paths - These paths are what routes are defined by. For instance, if a route is set up to direct a given HTTP request to a specific directory, then the URL path would be the directory path within the application’s root directory. The principle is the same as it is with typing a website in your browser;
• Middleware - This function can be executed at any point in a web application’s request-response cycle. They do not need to be at the cycle’s beginning or end. The cycle itself is the back and forth between the browser and the server, and middleware functions can work within that cycle and perform various side actions such as authentication, logging, validation, data parsing, and so on;
• Array - An array is another term not specific to Node.js, as it is a general computer programming term. It is used to describe a data structure which stores and organizes various items or elements;
• CSS - Cascading Style Sheets (CSS) is a stylesheet language. A stylesheet language is specifically used for describing the presentation and formatting of documents. In other words, it can define the visual styling of web documents, such as HTML web pages. CSS is used specifically for HTML web pages and can be used to edit and manage the appearance of such web pages;
• Class - A class in programming is a template for creating objects. It defines the attributes (properties) and methods (functions) that objects it creates will have;
• Object - Objects are the building blocks of JavaScript and, therefore, of Node.js. An object is an instance of a class or other data structure with attributes (properties) and methods (functions). Simply put, objects are created by classes, which define their data and behavior;
• Attributes - Also known as properties, attributes represent the data or characteristics of an object. They describe the state of an object and are used to store and manage related information. For instance, if you have an object in an application representing Cars, the attributes can include Color, Make, Model, and so on;
• Methods - While attributes describe the raw data within an object, a method – also known as function - describes how the object will behave and what actions it can perform.

There are likely many more terms that exist in the Node.js sphere, but these are some of the most important ones. You will likely encounter them most frequently.