Tags: dom

162

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Thursday, February 21st, 2019

A tiny lesson in query selection

We have a saying at Clearleft:

Everything is a tiny lesson.

I bet you learn something new every day, even if it’s something small. These small tips and techniques can easily get lost. They seem almost not worth sharing. But it’s the small stuff that takes the least effort to share, and often provides the most reward for someone else out there. Take for example, this great tip for getting assets out of Sketch that Cassie shared with me.

Cassie was working on a piece of JavaScript yesterday when we spotted a tiny lesson that tripped up both of us. The script was a fairly straightforward piece of DOM scripting. As a general rule, we do a sort of feature detection near the start of the script. Let’s say you’re using querySelector to get a reference to an element in the DOM:

var someElement = document.querySelector('.someClass');

Before going any further, check to make sure that the reference isn’t falsey (in other words, make sure that DOM node actually exists):

if (!someElement) return;

That will exit the script if there’s no element with a class of someClass on the page.

The situation that tripped us up was like this:

var myLinks = document.querySelectorAll('a.someClass');

if (!myLinks) return;

That should exit the script if there are no A elements with a class of someClass, right?

As it turns out, querySelectorAll is subtly different to querySelector. If you give querySelector a reference to non-existent element, it will return a value of null (I think). But querySelectorAll always returns an array (well, technically it’s a NodeList but same difference mostly). So if the selector you pass to querySelectorAll doesn’t match anything, it still returns an array, but the array is empty. That means instead of just testing for its existence, you need to test that it’s not empty by checking its length property:

if (!myLinks.length) return;

That’s a tiny lesson.

Friday, December 28th, 2018

Tumble log xyz

Kevin made this handy catch-all service for hosting Tumblr blogs on their own domain (which can bypass Tumblr’s annoying Oath interstital). Here’s mine.

Wednesday, December 12th, 2018

What’s the difference between JavaScript event delegation, bubbling, and capturing? | Go Make Things

I can never keep these straight—this is going to be a handy reference to keep on hand.

Sunday, September 9th, 2018

Removing jQuery from GitHub.com frontend | GitHub Engineering

You really don’t need jQuery any more …and that’s thanks to jQuery.

Here, the Github team talk through their process of swapping out jQuery for vanilla JavaScript, as well as their forays into web components (or at least the custom elements bit).

Friday, September 7th, 2018

881410 - Incorrect transforms when stripping subdomains

The latest version of Chrome is removing seams by messing with the display of the URL.

This is a bug.

Wednesday, September 5th, 2018

Daring Fireball: Medium Deprecates Custom Domains Service

I know many people love Medium’s editing interface, but I just can’t believe that so many writers and publications have turned toward a single centralized commercial entity as a proposed solution to what ails the publishing industry. There is tremendous strength in independence and decentralization.

Friday, July 13th, 2018

CSS: A New Kind Of JavaScript | HeydonWorks

A bold proposal by Heydon to make the process of styling on the web less painful and more scalable. I think it’s got legs, but do we really need another three-letter initialism?

We waste far too much time writing and maintaining styles with JavaScript, and I think it’s time for a change. Which is why it’s my pleasure to announce an emerging web standard called CSS.

Tuesday, July 10th, 2018

Web Components in 2018 - Blog | SitePen

A good explanation of web components, complete with some code examples.

Web Components are not a single technology. Instead, they are series of browser standards defined by the W3C allowing developers to build components in a way the browser can natively understand. These standards include:

  • HTML Templates and Slots – Reusable HTML markup with entry points for user-specific markup
  • Shadow DOM – DOM encapsulation for markup and styles
  • Custom Elements – Defining named custom HTML elements with specific behaviour

Wednesday, June 13th, 2018

designhumandesign

Refresh for a new design challenge.

Tuesday, June 5th, 2018

CORS

A thorough explanation of the history and inner workings of Cross-Origin Resource Sharing.

Like tales of a mythical sea beast, every developer has a story to tell about the day CORS seized upon one of their web requests, dragging it down into the inexorable depths, never to be seen again.

Monday, June 4th, 2018

Web Components Club – A journal about learning web components

Andy Bell is documenting is journey of getting to grips with web components. I think it’s so valuable to share like this as you’re learning, instead of waiting until you’ve learned it all—the fresh perspective is so useful!

Friday, June 1st, 2018

Let’s make the grimy architecture of the web visible again by Russell Davies

Beneath the URL shorteners, the web!

It’s increasingly apparent that a more digitally literate citizenry would be good for a thousand different reasons. A great way to start would be to make URLs visible again, to let people see the infrastructure they’re living in.

Tuesday, May 29th, 2018

Superfan! — Sacha Judd

The transcript of a talk that is fantastic in every sense.

Fans are organised, motivated, creative, technical, and frankly flat-out awe-inspiring.

Tuesday, May 22nd, 2018

Easy Toggle State

I think about 90% of the JavaScript I’ve ever written was some DOM scripting to handle the situation of “when the user triggers an event on this element, do something to this other element.” Toggles, lightboxes, accordions, tabs, tooltips …they’re all basically following the same underlying pattern. So it makes sense to me to see this pattern abstracted into a little library.

Tuesday, April 17th, 2018

An Introduction to the IndieWeb

A thorough run-down of the whys and wherefores of being part of the indie web, from Chris.

Thursday, April 12th, 2018

The Eponymous Laws of Tech - daverupert.com

Dave has curated a handy list of eponymous laws.

Thursday, April 5th, 2018

setInterval(_=>{ document.body.innerHTML = [ …”😮😀😁😐😑😬” ][~~(Math.random()*6)] },95)

A tiny snippet of JavaScript for making an animation of a talking emoji face.

Monday, February 26th, 2018

as days pass by — Collecting user data while protecting user privacy

Really smart thinking from Stuart on how the randomised response technique could be applied to analytics. My only question is who exactly does the implementation.

The key point here is that, if you’re collecting data about a load of users, you’re usually doing so in order to look at it in aggregate; to draw conclusions about the general trends and the general distribution of your user base. And it’s possible to do that data collection in ways that maintain the aggregate properties of it while making it hard or impossible for the company to use it to target individual users. That’s what we want here: some way that the company can still draw correct conclusions from all the data when collected together, while preventing them from targeting individuals or knowing what a specific person said.

Saturday, January 6th, 2018

A Sliding Nightmare: Understanding the Range Input | CSS-Tricks

Ana goes into exhaustive detail on all the differences in the shadow DOM and styling of input type="range" across browsers.

I’m totally fine with browsers providing different styling for complex UI elements like this, but I wish they’d at least provide a consistent internal structure and therefore a consistent way of over-riding the default styles. Maybe then people wouldn’t be so quick to abandon native elements like this in favour building their own UI components from scratch—the kind of over-engineering that inevitably ends up being under-engineered.

Friday, December 22nd, 2017

The web we may have lost | Christian Heilmann

The world-wide-web always scared the hell out of those who want to control what people consume and what their career is. The web was the equaliser.

A heartfelt missive by Christian on the eve of the US potentially losing net neutrality. I agree with every single word he’s written.

I hope that people still care that the web flows, no matter for whom or what the stream carries. The web did me a lot of good, and it can do so for many others. But it can’t do that if it turns into Cable TV. I’ve always seen the web as my media to control. To pick what I want to consume and question it by comparing it. A channel for me to publish and be scrutinised by others. A read-write medium. The only one we have. Let’s do more of the write part.