ABC's of JavaScript and Node.js - NodeSource

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ABC's of JavaScript and Node.js

In tech, terms and acronyms are everywhere.
Sometimes when we hear them, they can seem vaguely familiar; or maybe we've used them extensively, read them somewhere, or heard it briefly during a conversation. But how many of them do we really know and understand?

In this blog post, you can find a list of the most important terms in the JavaScript and Node.js ecosystem that you should know.

Did you know them all before? If we missed something, send us a DM on twitter



Application Programming Interface. A set of subroutine definitions, communication protocols, and tools for building software. In general terms, it is a set of clearly defined methods of communication among various components. An API specification can take many forms, but often includes specifications for routines, data structures, object classes, variables, or remote calls. Documentation for the API usually is provided to facilitate usage and implementation.


Application program, is a software program that runs on your computer. Web browsers, email programs, word processors, games, and utilities are all applications. The word "application" is used because each program has a specific application for the user. In other words, it’sa software designed to perform a group of coordinated functions, tasks, or activities for the benefit of the user.


Async functions enable us to write promise-based code as if it were synchronous, but without blocking the execution thread. It operates asynchronously via the event-loop. Async functions will always return a value. Using async simply implies that a promise will be returned, and if a promise is not returned, JavaScript automatically wraps it in a resolved promise with its value.


The await operator is used to wait for a Promise. It can be used inside an Async block only. The keyword Await makes JavaScript wait until the promise returns a result. It should be noted that it only makes the async function block wait and not the whole program execution.


Prior to the introduction of TypedArray, the JavaScript language had no mechanism for reading or manipulating streams of binary data. The Buffer class was introduced as part of the Node.js API to enable interaction with octet streams in TCP streams, file system operations, and other contexts. Instances of the Buffer class are similar to arrays of integers but correspond to fixed-sized, raw memory allocations outside the V8 heap. The size of the Buffer is established when it is created and cannot be changed.


A closure is the combination of a function and the lexical environment within which that function was declared. A closure is a function that has access to the parent scope, even after the parent function has closed.

Community Committee

The Community Committee (CommComm) is a top-level committee in the Node.js Foundation. The CommComm has authority over outward-facing community outreach efforts, including community evangelism, education initiatives, the cultural direction of node.js foundation, community organization outreach, translation and internationalization, project moderation/mediation, public outreach and publications.


A computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name “compiler” is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language, object code, or machine code) to create an executable program.


Concurrency refers to the execution of multiple tasks over a period of time. When it comes to computers and processors, some tasks can be executed in parallel and some tasks have to be done one at a time. But generally speaking, concurrency happens in order-independent or partially-ordered units of work.


Alternately referred to as a processor, central processor, or microprocessor, the CPU is the central processing unit of the computer. A computer's CPU handles all instructions it receives from hardware and software running on the computer.


In Node.js, the dependencies’ value is used to specify any other modules that a given module (represented by the package.json) requires to work. You can install the dependencies with a package manager in your root folder, run npm install or yarn install and it will install any modules listed in that dependencies hash.


Encompasses all processes involved in getting new software or hardware up and running properly in its environment, this includes installation, configuration, running, testing, and making necessary changes.


ECMAScript (or ES) is a scripting language specification standardized by Ecma International in ECMA-262 and ISO/IEC 16262. It was created to standardize JavaScript, so as to foster multiple independent implementations. JavaScript has remained the best-known implementation of ECMAScript since the standard was first published.

Event Loop

This is one of the most important aspects to understand about JavaScript. The Event Loop is what allows JavaScript to be asynchronous and have non-blocking I/O, — despite the fact that JavaScript is single-threaded — by offloading operations to the system kernel whenever possible through callbacks, promises and async/await.


A development environment is a collection of procedures and tools for developing, testing and debugging an application or program. The development environment normally has three server tiers, called development, staging and production. All three tiers together are usually referred to as the DSP.


A function is a block of organized, reusable code that is used to perform a single, related action. Functions provide better modularity for your application and a high degree of code reusing.


A software framework is a concrete or conceptual platform where common code with generic functionality can be selectively specialized or overridden by developers or users. Frameworks take the form of libraries, where a well-defined application program interface (API) is reusable anywhere within the software under development. Some examples of frameworks in Node.js include Express.js, Koa, Hapi, Nest, Restify and others.

Global Object

A global object is an object that always exists in the global scope. In JavaScript, there's always a global object defined. In a web browser, when scripts create global variables, they're created as members of the global object. (In Node.js this is not the case.) The global object's interface depends on the execution context in which the script is running.


A hostname is the label assigned to a device (a host) on a network and is used to distinguish one device from another on a specific network or over the internet.


The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser.


Each object in JavaScript is an instance of the object Object, therefore it inherits all its properties and methods. In other words, any object that derives from another object is called an instance. In this way, all objects are instances of another one, except the Object class, that is the parent class.


Often abbreviated as JS, is a high-level, interpreted scripting language that conforms to the ECMAScript specification. JavaScript has curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions. Alongside HTML and CSS, JavaScript is one of the core technologies of the World Wide Web. JavaScript enables interactive web pages and is an essential part of web applications. The vast majority of websites use it, and major web browsers have a dedicated JavaScript engine to execute it.


Keywords are tokens that have special meaning in JavaScript: break, case, catch, continue, debugger, default, delete, do, else, finally, for, function, if, in, instanceof, new, return, switch, this, throw, try, typeof, var, void, while, and with, and you cannot use these reserved words as variables, labels, or function names


Is a suite of data and programming code that is used to develop software programs and applications. It is designed to assist both the programmer and the programming language compiler in building and executing software.


A multi-platform support library that focuses on asynchronous I/O, primarily developed for use by Node.js.


(Don’t confuse it with TLS - as I do 😂) LTS is an acronym for Long-Term Support, and is applied to release lines that will be supported and maintained by the Node.js project for an extended period of time.

  • Active: An Active LTS release line is one that is being actively maintained and upgraded, including backporting newer non-breaking features, functionality, and improvements, addressing bugs, and patching security vulnerabilities.
  • Maintenance: A Maintenance LTS release line is a Node.js LTS release line that's nearing End of Life (EOL) and will only receive bug fixes and security patches for a short window of time.


Middleware functions are functions that have access to the request object (req), the response object (res), and the next function in the application’s request-response cycle. The next function is a function which, when invoked, executes the middleware succeeding the current middleware. Middleware functions can perform the following tasks:

  • Execute any code.
  • Make changes to the request and response objects.
  • End the request-response cycle.
  • Call the next middleware in the stack.


Module in Node.js is a simple or complex functionality organized in single or multiple JavaScript files that can be reused throughout the Node.js application. Each module in Node.js has its own context, so it cannot interfere with other modules or pollute global scope. Also, each module can be placed in a separate .js file under a separate folder.


A software platform that is used to build scalable network applications. Node.js uses JavaScript as its scripting language, and achieves high throughput via non-blocking I/O and a single-threaded event loop.


Is the world's largest Software Registry. The registry contains over 800,000 code packages, open-source developers use npm to share software and also, many organizations use npm to manage private development.


Node Version Manager is a tool that allows programmers to seamlessly switch between different versions of Node. You can install each version with a single command and set a default via the command-line


In JavaScript, an object is a standalone entity, with properties and type. Compare it with a cup, for example. A cup is an object, with properties. A cup has a color, a design, weight, a material it is made of, etc. The same way, JavaScript objects can have properties, which define their characteristics.

OpenJS Foundation

Node.js Foundation and the JS Foundation merged to form the OpenJS Foundation. The OpenJS Foundation is made up of 32 open source JavaScript projects including Appium, Dojo, jQuery, Node.js, and webpack. Their mission is to support the healthy growth of JavaScript and web technologies by providing a neutral organization to host and sustain projects, as well as collaboratively fund activities that benefit the ecosystem as a whole.


Open source software is software with source code that anyone can inspect, modify, and enhance. If a program is open-source, its source code is freely available to its users. Its users – and anyone else – have the ability to take this source code, modify it, and distribute their own versions of the program. The users also have the ability to distribute as many copies of the original program as preferred. Anyone can use the program for any purpose; there are no licensing fees or other restrictions on the software.


A software package is multiple applications or code modules that work together to meet various goals and objectives. A package in Node.js contains all the files you need for a module. Modules are JavaScript libraries you can include in your project.


A package.json file lists the packages your project depends on, specifies versions of a package that your project can use using semantic versioning rule, and makes your build reproducible, and therefore easier to share with other developers.

Package Manager

Is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer's operating system in a consistent manner. A package manager deals with packages, distributions of software and data in archive files. Packages contain metadata, such as the software's name, description of its purpose, version number, vendor, and a list of dependencies necessary for the software to run properly. Upon installation, metadata is stored in a local package database. Package managers typically maintain a database of software dependencies and version information to prevent software mismatches and missing prerequisites.


Is a "logical connection place" and specifically, using the Internet's protocol, the way a client program specifies a particular server program on a computer in a network. Higher-level applications that use TCP/IP such as the Web protocol, Hypertext Transfer Protocol, have ports with preassigned numbers. Other application processes are given port numbers dynamically for each connection. When a service (server program) initially is started, it is said to bind to its designated port number. As any client program wants to use that server, it also must request to bind to the designated port number.


Is the instance of a computer program that is being executed by one or many threads. It contains the program code and its activity. Depending on the operating system, a process may be made up of multiple threads of execution that execute instructions concurrently.


The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.


A query is a request for data or information from a database table or combination of tables. This data may be generated as results returned by Structured Query Language (SQL) or as pictorials, graphs or complex results, e.g., trend analyses from data-mining tools. One of several different query languages may be used to perform a range of simple to complex database queries. SQL, the most well-known and widely-used query language, is familiar to most database administrators.


An HTTP request. A client submits an HTTP request message to a server, which returns a response. The request must use one of several request methods such as GET, POST, and so on.


An HTTP response. A server returns an HTTP response message to the client. The response contains completion status information about the request and might also contain requested content in its message body.


A read–eval–print loop (REPL), also termed an interactive top level or language shell, is a simple, interactive computer programming environment that takes single user inputs (i.e., single expressions), evaluates (executes) them, and returns the result to the user; a program written in a REPL environment is executed piecewise.


Refers to determining how an application responds to a client request to a particular endpoint, which is a URI (or path) and a specific HTTP request method (GET, POST, and so on). Each route can have one or more handler functions, which are executed when the route is matched.


Is a general term that refers to any library, framework, or platform that your code runs on. It describes software/instructions that are executed while your program is running, especially those instructions that you did not write explicitly, but are necessary for the proper execution of your code. Node.js is an open source, cross-platform runtime environment for developing server-side and networking applications.


Scope is the set of variables that’s visible to a part of the program.


Also known as standard error, is the default file descriptor where a process can write error messages. It’s an output stream typically used by programs to output error messages or diagnostics.


Also known as standard input, is stream data (often text) going into a program. The program requests data transfers by use of the read operation. It’s an input stream where data is sent to and read by a program.


Also known as standard output, is the stream where a program writes its output data. The program requests data transfer with the write operation. Not all programs generate output. For example, the file rename command (variously called mv, move, or ren) is silent on success.


Streams are collections of data — just like arrays or strings. The difference is that streams might not be available all at once, and they don’t have to fit in memory. This makes streams really powerful when working with large amounts of data, or data that’s coming from an external source one chunk at a time. However, streams are not only about working with big data. They also give us the power of composability in our code. Just like we can compose powerful linux commands by piping other smaller Linux commands, we can do exactly the same in Node with streams.


TC39 means Technical Committee number 39. It is part of ECMA, the institution which standardizes the JavaScript language under the “ECMAScript” specification. It works on the standardization of the general purpose, cross platform, vendor-neutral programming language that is ECMAScript. This includes the language syntax, semantics, libraries, and complementary technologies that support the language.


Transport Layer Security (TLS), and its now-deprecated predecessor, Secure Sockets Layer (SSL) are cryptographic protocols designed to provide communications security over a computer network. Several versions of the protocols find widespread use in applications such as web browsing, email, instant messaging, and voice over IP (VoIP). Websites can use TLS to secure all communications between their servers and web browsers.


TSC or Technical Steering Committee is the technical governing body of the Node.js Foundation and is responsible for the Node.js Core project, a number of projects depended upon by Node.js Core, and a number of projects adjacent to Node.js Core. The TSC exercises autonomy in managing its responsibilities and seeks agreement from the Node.js Foundation Board


JavaScript is single-threaded, meaning that only one set of instructions is executed at a time in a given process.


The util module in Node.js is primarily designed to support the needs of Node.js' own internal APIs. However, many of the utilities are useful for application and module developers as well. It can be accessed using: const util = require('util');.


Is the name of the JavaScript engine that powers Google Chrome. It's the thing that takes our JavaScript and executes it while browsing with Chrome. V8 provides the runtime environment in which JavaScript executes. The DOM, and the other Web Platform APIs are provided by the browser.

Worker Threads

The worker_threads module enables the use of threads that execute JavaScript in parallel. To access it: const worker = require('worker_threads');.
Workers (threads) are useful for performing CPU-intensive JavaScript operations. They will not help much with I/O-intensive work. Node.js’s built-in asynchronous I/O operations are more efficient than Workers can be. For more information visit this blog post.


Use XMLHttpRequest (XHR) objects to interact with servers. You can retrieve data from a URL without having to do a full page refresh. This enables a Web page to update just part of a page without disrupting what the user is doing. XMLHttpRequest is used heavily in AJAX programming.


Fast, reliable, and secure dependency management. Yarn is a package manager for your code. It allows you to use and share code with other developers from around the world.


The zlib module in Node.js provides compression functionality implemented using Gzip and Deflate/Inflate. It can be accessed using: const zlib = require('zlib');.
Compressing or decompressing a stream (such as a file) can be accomplished by piping the source stream data through a zlib stream into a destination stream.

One Last Thing...

If you want to keep up to date on the Node.js community and what's happening across the ecosystem, you should be sure to check out @NodeSource on Twitter. We try to spread the word as far and wide as possible about the awesome things that are always happening in the community.


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