Deno is a new runtime environment for JavaScript and TypeScript. Deno founder Ryan Dahl, who was also the founding developer of Node.js, says Deno is intended to be a more modern version of Node.js.
When Node.js was first released, in 2009, JavaScript didn’t have the async-await mechanism, typed arrays, or the ECMAScript module system. At the time, Dahl recognized that an event loop would be an essential resource for server-side JavaScript and set to work on creating a runtime environment that included one.
By 2012, Dahl felt the primary goal of creating a user-friendly non-blocking framework had been achieved, with Node.js having support for multiple protocols, cross-platform support, a relatively stable API, and a growing ecosystem of external modules distributed through npm.
But over time it became apparent to Dahl that a number of design decisions, like the early removal of Promises, caused problems. Security, the GYP build system, and...
Since its beginning as a primitive, unstandardized scripting language for web browsers, JavaScript has gained many features that better equip it for handling common programming tasks. Some of the most important improvements are in the area of handling asynchronous events like form submission, user interface interaction, and media management.
The growth of server-side JavaScript enabled by Node.js has substantially expanded the range of project types and business challenges JavaScript can successfully address, adding new requirements for asynchronous processing. The popularity of web services as a design paradigm and REST APIs as an interaction standard have both added to the scope of asynchronous tasks for the language.
The Node package management system, npm, makes it possible to easily integrate capabilities provided in open source libraries. Packages for asynchronous tasks have been some of the most successful of these, adding programming paradigms to JavaScript that were unimagined in the early days of...
In JavaScript, like many programming languages, asynchronous processing can be used to handle tasks that take a long time to run or are potentially unresponsive. The JavaScript Promise object provides a way of monitoring their state and serves as a placeholder and container for the data they’ll eventually return — or not.
Often it doesn’t matter when a Promise returns data and the members of a collection of Promises can be resolved independently without regard to timing. A function can perform asynchronous tasks that don’t depend on the data from, or the success of, other asynchronous tasks.
But sometimes business rules or program design require that asynchronous actions are dependent on other asynchronous operations. For example...
Asynchronous processing is one of the most important aspects of the JavaScript language. JavaScript is a single-threaded language, so it needs a mechanism to deal with the actions like performing time-intensive and potentially unreliable activities like making REST API calls, reading files from the disk, or interacting with user input.
In JavaScript the mechanism used is an event loop, which processes a callback queue in order from oldest item to newest. Each item in the queue is a message that’s processed completely before moving on to the next next message. Each message is a function that returns a response to code elsewhere in the application. Functions used in this way are called callback functions.
Because of callbacks, JavaScript can use a number of techniques for getting around its single-threaded nature to implement asynchronous processing. Unfortunately, some of those techniques, JavaScript Promises and RxJS Observables, force you to introduce at...
Are you a developer looking for a new hobby that’s compatible with sheltering in place? Would you like to be able to share it with friends from a virus-safe distance?
You can stargaze from the safety of your own lawn, balcony, or roof, and you don’t need any equipment other than your own eyes, and maybe a pair of binoculars. There are plenty of bright objects in the night sky that are visible with the naked eye. One of them is the International Space Station (ISS), which is the third brightest object in the sky after the sun and moon.
The ISS whips around the earth at 27,576 kilometers per hour (17,000 miles per hour), making a complete orbit every 94 minutes. Opportunities to observe it only last a few minutes, so it’s helpful to know when the ISS will be visible and from which direction it will appear.