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Nalezeno "javascript": 114

Understanding Async Await


When writing code for the web, eventually you'll need to do some process that might take a few moments to complete. JavaScript can't really multitask, so we'll need a way to handle those long-running processes. Async/Await is a way to handle this type of time-based sequencing. It’s especially great...

let vs. const


There are multiple ways to declare variables in JavaScript. We had var, and while that still works like it always has, it is generally said that let and const are replacements to the point we rarely (if ever) need var anymore. This doodle explanation does a pretty good job, if you need...

Duplicated Argument Names


Oftentimes we override or monkey patch functions and, in many cases, there are arguments we don’t care too much about. A common practice for those arguments is using _ for argument names — it’s a generally accepted and known practice for “this isn’t important”....

One Way to Break Users Out of the Habit of Reloading Too Much


Page reloads are a thing. Sometimes we refresh a page when we think it’s unresponsive, or believe that new content is available. Sometimes we’re just mad at the dang site and rage-refresh to let it know we’re displeased. Wouldn’t be nice to know when a user refreshes the page? Not just that,...

JavaScript ~~


JavaScript is loaded with tiny syntax tricks to accomplish useful effects. For example, explore any codebase to see !! being used to convert a value to a boolean value. Have you seen ~~ before? Let’s have a look at what it does! We can employ ~~ to trigger a Math.floor operation with those...

Build your own React


Wowza! Rodrigo Pombo’s article about how to build React from scratch is fantastic, not only because it’s well written, but because of the outstanding interaction design: each line in the code examples ge highlighted and explored in further detail as you scroll down the page. This makes it super...

React Hooks, které potřebujete znát


React s verzí 16.8 přináší zásadní novinku, a tou jsou Hooks, které mají přinést řešení pro hned 3 největší problémy, se kterými se v Reactu potýkáme. Implementace komponent pomocí tříd, sdílení logiky, nepraktický způsob práce s životním cyklem komponent. Představíme vám React Hooks a na konci...

What is super() in JavaScript?


What's happening when you see some JavaScript that calls super()?.In a child class, you use super() to call its parent’s constructor and super.<methodName> to access its parent’s methods. This article will assume at least a little familiarity with the concepts of constructors and child...

JavaScript waitForTime


I write a lot of tests for new features within Firefox DevTools. We have hundreds of “mochitests” which open the browser and perform synthetic actions like clicking, typing, and other user actions. I’ve previously written about waitForever which essentially halts following actions...

Comparing the Different Types of Native JavaScript Popups


JavaScript has a variety of built-in popup APIs that display special UI for user interaction. Famously: alert("Hello, World!"); The UI for this varies from browser to browser, but generally you’ll see a little window pop up front and center in a very show-stopping way that contains the message...

How to Create a QR Code


QR codes aren’t everyone’s cup of tea but I quite like them. If I see something I want to remember or check out later, especially when on the road, it’s super easy to take a quick picture — it’s much easier than trying to remember a URL and much faster than typing...

Jaká byla Nordic.js 2019


Série evropských JavaScriptových konferencí JSConf zaznamenala letos výraznou změnu, když její hlavní a zakládající berlínská odnož oznámila ukončení svého působení. Tíha zodpovědnosti se tak přesouvá na ostatní regionální organizátory

How to Detect an Ad Blocker


One of the unspoken rules of the internet is that most content is “free”… at the cost of webpage being littered with advertisements and trackers. This was’t a big problem in the early internet days but trackers and advertisements have become so intrusive and unapologetically...

designMode


Every once in a while I stumble upon an API or browser setting that I can’t believe ever existed. Such examples can be seen in the numerous String.prototype properties such as bold, italics, and even blink, which wrap given string text in their representative HTML tags. Bizarre. It...

“Off The Main Thread”


JavaScript is what they call "single-threaded." As Brian Barbour puts it: This means it has one call stack and one memory heap. We all feel a symptom of that regularly in the form of performance jank and non-interactivity on elements or entire sites. If we give JavaScript lots of jobs and it gets...

How to Not Minify Source with webpack


The webpack JavaScript utility has taken over the modern JavaScript landscape, so much so that it’s hard to be a JavaScript developer and not use it. JavaScript build utilities are the point where they do best practices implicitly, like minify code, caching, and more. I was recently debugging...

Stop Installing Packages Globally


These days, most front-end projects are going to involve NPM packages of some kind. Occasionally, when browsing documentation for these packages, I’ll see a recommendation to install a package like this. yarn global add <package> Or like this. npm install --global <package> In both...

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