Tags: images

167

sparkline

Tuesday, September 11th, 2018

The top four web performance challenges

Danielle and I have been doing some front-end consultancy for a local client recently.

We’ve both been enjoying it a lot—it’s exhausting but rewarding work. So if you’d like us to come in and spend a few days with your company’s dev team, please get in touch.

I’ve certainly enjoyed the opportunity to watch Danielle in action, leading a workshop on refactoring React components in a pattern library. She’s incredibly knowledgable in that area.

I’m clueless when it comes to React, but I really enjoy getting down to the nitty-gritty of browser features—HTML, CSS, and JavaScript APIs. Our skillsets complement one another nicely.

This recent work was what prompted my thoughts around the principles of robustness and least power. We spent a day evaluating a continuum of related front-end concerns: semantics, accessibility, performance, and SEO.

When it came to performance, a lot of the work was around figuring out the most suitable metric to prioritise:

  • time to first byte,
  • time to first render,
  • time to first meaningful paint, or
  • time to first meaningful interaction.

And that doesn’t even cover the more easily-measurable numbers like:

  • overall file size,
  • number of requests, or
  • pagespeed insights score.

One outcome was to realise that there’s a tendency (in performance, accessibility, or SEO) to focus on what’s easily measureable, not because it’s necessarily what matters, but precisely because it is easy to measure.

Then we got down to some nuts’n’bolts technology decisions. I took a step back and looked at the state of performance across the web. I thought it would be fun to rank the most troublesome technologies in order of tricksiness. I came up with a top four list.

Here we go, counting down from four to the number one spot…

4. Web fonts

Coming in at number four, it’s web fonts. Sometimes it’s the combined weight of multiple font files that’s the problem, but more often that not, it’s the perceived performance that suffers (mostly because of when the web fonts appear).

Fortunately there’s a straightforward question to ask in this situation: WWZD—What Would Zach Do?

3. Images

At the number three spot, it’s images. There are more of them and they just seem to be getting bigger all the time. And yet, we have more tools at our disposal than ever—better file formats, and excellent browser support for responsive images. Heck, we’re even getting the ability to lazy load images in HTML now.

So, as with web fonts, it feels like the impact of images on performance can be handled, as long as you give them some time and attention.

2. Our JavaScript

Just missing out on making the top spot is the JavaScript that we send down the pipe to our long-suffering users. There’s nothing wrong with the code itself—I’m sure it’s very good. There’s just too damn much of it. And that’s a real performance bottleneck, especially on mobile.

So stop sending so much JavaScript—a solution as simple as Monty Python’s instructions for playing the flute.

1. Other people’s JavaScript

At number one with a bullet, it’s all the crap that someone else tells us to put on our websites. Analytics. Ads. Trackers. Beacons. “It’s just one little script”, they say. And then that one little script calls in another, and another, and another.

It’s so disheartening when you’ve devoted your time and energy into your web font loading strategy, and optimising your images, and unbundling your JavaScript …only to have someone else’s JavaScript just shit all over your nice performance budget.

Here’s the really annoying thing: when I go to performance conferences, or participate in performance discussions, you know who’s nowhere to be found? The people making those third-party scripts.

The narrative around front-end performance is that it’s up to us developers to take responsibility for how our websites perform. But by far the biggest performance impact comes from third-party scripts.

There is a solution to this, but it’s not a technical one. We could refuse to add overweight (and in many cases, unethical) third-party scripts to the sites we build.

I have many, many issues with Google’s AMP project, but I completely acknowledge that it solves a political problem:

No external JavaScript is allowed in an AMP HTML document. This covers third-party libraries, advertising and tracking scripts. This is A-okay with me.

The reasons given for this ban are related to performance and I agree with them completely. Big bloated JavaScript libraries are one of the biggest performance killers on the web.

But how can we take that lesson from AMP and apply it to all our web pages? If we simply refuse to be the one to add those third-party scripts, we get fired, and somebody else comes in who is willing to poison web pages with third-party scripts. There’s nothing to stop companies doing that.

Unless…

Suppose we were to all make a pact that we would stand in solidarity with any of our fellow developers in that sort of situation. A sort of joining-together. A union, if you will.

There is power in a factory, power in the land, power in the hands of the worker, but it all amounts to nothing if together we don’t stand.

There is power in a union.

Thursday, August 2nd, 2018

Dynamic resources using the Network Information API and service workers

Smart thinking—similar to this post from last year—about using the navigator.connection API from a service worker to serve up bandwidth-appropriate images.

This is giving me some ideas for my own site.

Sunday, July 1st, 2018

Sunday, June 17th, 2018

Detecting image requests in service workers

In Going Offline, I dive into the many different ways you can use a service worker to handle requests. You can filter by the URL, for example; treating requests for pages under /blog or /articles differently from other requests. Or you can filter by file type. That way, you can treat requests for, say, images very differently to requests for HTML pages.

One of the ways to check what kind of request you’re dealing with is to see what’s in the accept header. Here’s how I show the test for HTML pages:

if (request.headers.get('Accept').includes('text/html')) {
    // Handle your page requests here.
}

So, logically enough, I show the same technique for detecting image requests:

if (request.headers.get('Accept').includes('image')) {
    // Handle your image requests here.
}

That should catch any files that have image in the request’s accept header, like image/png or image/jpeg or image/svg+xml and so on.

But there’s a problem. Both Safari and Firefox now use a much broader accept header: */*

My if statement evaluates to false in those browsers. Sebastian Eberlein wrote about his workaround for this issue, which involves looking at file extensions instead:

if (request.url.match(/\.(jpe?g|png|gif|svg)$/)) {
    // Handle your image requests here.
}

So consider this post a patch for chapter five of Going Offline (page 68 specifically). Wherever you see:

if (request.headers.get('Accept').includes('image'))

Swap it out for:

if (request.url.match(/\.(jpe?g|png|gif|svg)$/))

And feel to add any other image file extensions (like webp) in there too.

Wednesday, May 23rd, 2018

The Tarot Cards Of Tech

A useful set of questions to ask on any project, shuffled and dealt to you.

They’ll not only help you foresee unintended consequences—they can also reveal opportunities for positive change.

All of the content in images. Not a single image has alternative text. If only they had asked themselves:

When you picture your user base, who is excluded? If they used your product, what would their experience be like?

Sunday, April 15th, 2018

Keep Pixelated Images Pixelated as They Scale | CSS-Tricks

This is a potentially useful bit of CSS that I had no idea existed.

Friday, April 6th, 2018

Lazy Loading Images and Video  |  Web Fundamentals  |  Google Developers

Jeremy Wagner offers a deep dive into lazy loading images (and video) with some advice for considering the no-JavaScript situation too.

Wednesday, April 4th, 2018

Carbon

This service could be quite handy if you’re making a presentation that involves showing code—it generates syntax-highlighted images of code.

Tuesday, March 27th, 2018

Compressive Images Revisited - TimKadlec.com

Tim explains why that neat trick of making a really big JPEG with quality set to 0% is no longer necessary, and how the savings you make in bandwidth with that technique are nullified by the expense of the memory footprint needed.

Monday, March 12th, 2018

Swapping Images with the Sizes Attribute | Filament Group, Inc., Boston, MA

The hits just keep on coming from the Filament Group. Here Scott shares a really clever technique for creating an image magnifier using the sizes attribute of the img element.

Wednesday, March 7th, 2018

Boxy SVG

This is impressive—a fully featured graphics app for creating SVGS right in your browser.

Metaballs

Metaballs, not to be confused with meatballs, are organic looking squishy gooey blobs.

Here’s the maths behind the metaballs (implemented in SVG).

Friday, February 9th, 2018

Href Tools - Free online web tools

Handy web-based tools—compress HTML, CSS, and JavaScript, and convert files from one format to another.

Wednesday, November 29th, 2017

edent/SuperTinyIcons: Under 1KB each! Super Tiny Icons are miniscule SVG versions of your favourite website and app logos

These are lovely little SVGs of website logos that are yours for the taking. And if you want to contribute an icon to the collection, go for it …as long as it’s less than 1024 bytes (most of these are waaay less).

Monday, November 27th, 2017

Network based image loading using the Network Information API in Service Worker | justmarkup

This is clever—you can use the navigator.connection API from a service worker (because it’s asynchronous) which means you can have a service worker script that serves differently sized images based on bandwidth.

Saturday, November 18th, 2017

Using SVG as placeholders — More Image Loading Techniques - JMPerez Blog

Here’s a clever to technique to improve the perceived performance of image loading with a polygonal SVG placeholder.

Thursday, November 9th, 2017

The Contrast Swap Technique: Improved Image Performance with CSS Filters | CSS-Tricks

A clever performance trick for images:

  1. Reduce image contrast using a linear transform function (Photoshop can do this)
  2. Apply a contrast filter in CSS to the image to make up for the contrast removal

Wednesday, November 8th, 2017

Jupiter Perijove 09 | Flickr

Gorgeous images from Juno’s closest approach to Jupiter.

Perijove 09

Wednesday, November 1st, 2017

Rebuilding slack.com – Several People Are Coding

A really great case study of a code refactor by Mina, with particular emphasis on the benefits of CSS Grid, fluid typography, and accessibility.

Sunday, October 29th, 2017

Seeing Earth from Outer Space

A lovely interactive photo essay charting the results of what happens when evolution produces a life form that allows a planet to take selfies.