Tags: work

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Friday, August 9th, 2019

Time to First Byte: What It Is and Why It Matters by Harry Roberts

Harry takes a deep dive into the performance metric of “time to first byte”, or TTFB if you using initialisms that take as long to say as the thing they’re abbreviating.

This makes a great companion piece to Drew’s article on server timing headers.

Thursday, August 1st, 2019

Navigation preloads in service workers

There’s a feature in service workers called navigation preloads. It’s relatively recent, so it isn’t supported in every browser, but it’s still well worth using.

Here’s the problem it solves…

If someone makes a return visit to your site, and the service worker you installed on their machine isn’t active yet, the service worker boots up, and then executes its instructions. If those instructions say “fetch the page from the network”, then you’re basically telling the browser to do what it would’ve done anyway if there were no service worker installed. The only difference is that there’s been a slight delay because the service worker had to boot up first.

  1. The service worker activates.
  2. The service worker fetches the file.
  3. The service worker does something with the response.

It’s not a massive performance hit, but it’s still a bit annoying. It would be better if the service worker could boot up and still be requesting the page at the same time, like it would do if no service worker were present. That’s where navigation preloads come in.

  1. The service worker activates while simultaneously requesting the file.
  2. The service worker does something with the response.

Navigation preloads—like the name suggests—are only initiated when someone navigates to a URL on your site, either by following a link, or a bookmark, or by typing a URL directly into a browser. Navigation preloads don’t apply to requests made by a web page for things like images, style sheets, and scripts. By the time a request is made for one of those, the service worker is already up and running.

To enable navigation preloads, call the enable() method on registration.navigationPreload during the activate event in your service worker script. But first do a little feature detection to make sure registration.navigationPreload exists in this browser:

if (registration.navigationPreload) {
  addEventListener('activate', activateEvent => {
    activateEvent.waitUntil(
      registration.navigationPreload.enable()
    );
  });
}

If you’ve already got event listeners on the activate event, that’s absolutely fine: addEventListener isn’t exclusive—you can use it to assign multiple tasks to the same event.

Now you need to make use of navigation preloads when you’re responding to fetch events. So if your strategy is to look in the cache first, there’s probably no point enabling navigation preloads. But if your default strategy is to fetch a page from the network, this will help.

Let’s say your current strategy for handling page requests looks like this:

addEventListener('fetch', fetchEvent => {
  const request = fetchEvent.request;
  if (request.headers.get('Accept').includes('text/html')) {
    fetchEvent.respondWith(
      fetch(request)
      .then( responseFromFetch => {
        // maybe cache this response for later here.
        return responseFromFetch;
      })
      .catch( fetchError => {
        return caches.match(request)
        .then( responseFromCache => {
          return responseFromCache || caches.match('/offline');
        });
      })
    );
  }
});

That’s a fairly standard strategy: try the network first; if that doesn’t work, try the cache; as a last resort, show an offline page.

It’s that first step (“try the network first”) that can benefit from navigation preloads. If a preload request is already in flight, you’ll want to use that instead of firing off a new fetch request. Otherwise you’re making two requests for the same file.

To find out if a preload request is underway, you can check for the existence of the preloadResponse promise, which will be made available as a property of the fetch event you’re handling:

fetchEvent.preloadResponse

If that exists, you’ll want to use it instead of fetch(request).

if (fetchEvent.preloadResponse) {
  // do something with fetchEvent.preloadResponse
} else {
  // do something with fetch(request)
}

You could structure your code like this:

addEventListener('fetch', fetchEvent => {
  const request = fetchEvent.request;
  if (request.headers.get('Accept').includes('text/html')) {
    if (fetchEvent.preloadResponse) {
      fetchEvent.respondWith(
        fetchEvent.preloadResponse
        .then( responseFromPreload => {
          // maybe cache this response for later here.
          return responseFromPreload;
        })
        .catch( preloadError => {
          return caches.match(request)
          .then( responseFromCache => {
            return responseFromCache || caches.match('/offline');
          });
        })
      );
    } else {
      fetchEvent.respondWith(
        fetch(request)
        .then( responseFromFetch => {
          // maybe cache this response for later here.
          return responseFromFetch;
        })
        .catch( fetchError => {
          return caches.match(request)
          .then( responseFromCache => {
            return responseFromCache || caches.match('/offline');
          });
        })
      );
    }
  }
});

But that’s not very DRY. Your logic is identical, regardless of whether the response is coming from fetch(request) or from fetchEvent.preloadResponse. It would be better if you could minimise the amount of duplication.

One way of doing that is to abstract away the promise you’re going to use into a variable. Let’s call it retrieve. If a preload is underway, we’ll assign it to that variable:

let retrieve;
if (fetchEvent.preloadResponse) {
  retrieve = fetchEvent.preloadResponse;
}

If there is no preload happening (or this browser doesn’t support it), assign a regular fetch request to the retrieve variable:

let retrieve;
if (fetchEvent.preloadResponse) {
  retrieve = fetchEvent.preloadResponse;
} else {
  retrieve = fetch(request);
}

If you like, you can squash that into a ternary operator:

const retrieve = fetchEvent.preloadResponse ? fetchEvent.preloadResponse : fetch(request);

Use whichever syntax you find more readable.

Now you can apply the same logic, regardless of whether retrieve is a preload navigation or a fetch request:

addEventListener('fetch', fetchEvent => {
  const request = fetchEvent.request;
  if (request.headers.get('Accept').includes('text/html')) {
    const retrieve = fetchEvent.preloadResponse ? fetchEvent.preloadResponse : fetch(request);
    fetchEvent.respondWith(
      retrieve
      .then( responseFromRetrieve => {
        // maybe cache this response for later here.
       return responseFromRetrieve;
      })
      .catch( fetchError => {
        return caches.match(request)
        .then( responseFromCache => {
          return responseFromCache || caches.match('/offline');
        });
      })
    );
  }
});

I think that’s the least invasive way to update your existing service worker script to take advantage of navigation preloads.

Like I said, preload navigations can give a bit of a performance boost if you’re using a network-first strategy. That’s what I’m doing here on adactio.com and on thesession.org so I’ve updated their service workers to take advantage of navigation preloads. But on Resilient Web Design, which uses a cache-first strategy, there wouldn’t be much point enabling navigation preloads.

Jeff Posnick made this point in his write-up of bringing service workers to Google search:

Adding a service worker to your web app means inserting an additional piece of JavaScript that needs to be loaded and executed before your web app gets responses to its requests. If those responses end up coming from a local cache rather than from the network, then the overhead of running the service worker is usually negligible in comparison to the performance win from going cache-first. But if you know that your service worker always has to consult the network when handling navigation requests, using navigation preload is a crucial performance win.

Oh, and those browsers that don’t yet support navigation preloads? No problem. It’s a progressive enhancement. Everything still works just like it did before. And having a service worker on your site in the first place is itself a progressive enhancement. So enabling navigation preloads is like a progressive enhancement within a progressive enhancement. It’s progressive enhancements all the way down!

By the way, if all of this service worker stuff sounds like gibberish, but you wish you understood it, I think my book, Going Offline, will prove quite valuable.

The web without the web - DEV Community 👩‍💻👨‍💻

I love React. I love how server side rendering React apps is trivial because it all compiles down to vanilla HTML rather than web components, effectively turning it into a kickass template engine that can come alive. I love the way you can very effectively still do progressive enhancement by using completely semantic markup and then letting hydration do more to it.

I also hate React. I hate React because these behaviours are not defaults. React is not gonna warn you if you make a form using divs and unlabelled textboxes and send the whole thing to a server. I hate React because CSS-in-JS approaches by default encourage you to write completely self contained one off components rather than trying to build a website UI up as a whole. I hate the way server side rendering and progressive enhancement are not defaults, but rather things you have to go out of your way to do.

An absolutely brilliant post by Laura on how the priorites baked into JavaScript tools like React are really out of whack. They’ll make sure your behind-the-scenes code is super clean, but not give a rat’s ass for the quality of the output that users have to interact with.

And if you want to adjust the front-end code, you’ve got to set up all this tooling just to change a div to a button. That’s quite a barrier to entry.

In elevating frontend to the land of Serious Code we have not just made things incredibly over-engineered but we have also set fire to all the ladders that we used to get up here in the first place.

AMEN!

I love React because it lets me do my best work faster and more easily. I hate React because the culture around it more than the library itself actively prevents other people from doing their best work.

The Crowd and the Cosmos - Chris Lintott - Oxford University Press

This’ll be good—the inside story of the marvelous Zooniverse project as told by Chris Lintott. I’m looking forward to getting my hands on a copy of this book when it comes out in a couple of months.

Ooops, I guess we’re full-stack developers now.

Chris broke both his arms just to avoid speaking at the JAMstack conference in London. Seems a bit extreme to me.

Anyway, to make up for not being there, he made a website of his talk. It’s good stuff, tackling the split.

It’s cool to see the tech around our job evolve to the point that we can reach our arms around the whole thing. It’s worthy of some concern when we feel like complication of web technology feels like it’s raising the barrier to entry

Wednesday, July 31st, 2019

The Real Dark Web

Charlie’s thoughts on dev perception:

People speak about “the old guard” and “stupid backwards techniques”, forgetting that it’s real humans, with real constraints who are working on these solutions. Most of us are working in a “stupid backwards way” because that “backwardsness” WORKS. It is something that is proven and is clearly documented. We can implement it confident that it will not disappear from fashion within a couple of years.

Tuesday, July 30th, 2019

Don’t build that app! – Luke Jackson - YouTube

This is a fascinating look at how you can get the benefits of React and npm without using React and npm.

Here’s an accompanying article on the same topic.

Thursday, July 25th, 2019

What I Like About Vue - daverupert.com

Dave enumerates the things about Vue that click for him. The component structure matches his mental model, and crucially, it’s relative straightforward to add Vue to an existing project instead of ripping everything out and doing things a certain way:

In my experience Angular, React, and a lot of other frameworks ultimately require you to go all in early and establish a large toolchain around these frameworks.

Wednesday, July 24th, 2019

Jon Aizlewood · Agile and design — How to avoid Frankensteining your product

Jon’s ranting about Agile here, but it could equally apply to design systems:

Agile and design is like looking at a picture through a keyhole. By slicing big things into smaller things, designers must work incrementally. Its this incrementalism that can lead to what I call the ‘Frankensteining’ of a digital product or service.

Sunday, July 21st, 2019

Frontend Design, React, and a Bridge over the Great Divide

Brad describes how he has found his place in the world of React, creating UI components without dabbling in business logic:

Instead of merely creating components’ reference HTML, CSS, and presentational JS, frontend designers can create directly consumable HTML, CSS, and presentational JS that back-of-the-frontend developers can then breathe life into.

What’s clear is that the term “React” has become as broad and undefined as the term “front-end”. Just saying that someone does React doesn’t actually say much about the nature of the work.

When you say “we’re hiring a React developer”, what exactly do you mean by that? “React developer” is almost as vague as “frontend developer”, so clarify. Are you looking for a person to specialize in markup and styles? A person to author middleware and business logic? A person to manage data and databases? A person to own build processes?

Friday, July 19th, 2019

Micro Frontends

Chris succinctly describes the multiple-iframes-with-multiple-codebases approach to web development, AKA “micro frontends”:

The idea really is that you might build a React app and I build a Vue app and we’ll slap ‘em together on the same page. I definitely come from an era where we laughed-then-winced when we found sites that used multiple versions of jQuery on the same page, plus one thing that loaded all of MooTools and Prototype thrown on there seemingly by accident. We winced because that was a bucket full of JavaScript, mostly duplicated for no reason, causing bugs and slowing down the page. This doesn’t seem all that much different.

Thursday, July 18th, 2019

Ralph Lavelle: On resilience

Thoughts on frameworks, prompted by a re-reading of Resilient Web Design. I quite like the book being described as a “a bird’s-eye view of the whole web design circus.”

Monday, July 15th, 2019

How to run a small social network site for your friends

This is a great how-to from Darius Kazemi!

The main reason to run a small social network site is that you can create an online environment tailored to the needs of your community in a way that a big corporation like Facebook or Twitter never could. Yes, you can always start a Facebook Group for your community and moderate that how you like, but only within certain bounds set by Facebook. If you (or your community) run the whole site, then you are ultimately the boss of what goes on. It is harder work than letting Facebook or Twitter or Slack or Basecamp or whoever else take care of everything, but I believe it’s worth it.

There’s a lot of good advice for community management and the whole thing is a lesson in writing excellent documentation.

Friday, July 5th, 2019

Smashing TV — Webinars and Live Sessions — Smashing Magazine

Don’t miss this—a masterclass in SVG animation with Cassie (I refuse to use the W word). Mark your calendar: August 20th.

Thursday, July 4th, 2019

Movie Knight

I mentioned how much I enjoyed Mike Hill’s talk at Beyond Tellerrand in Düsseldorf:

Mike gave a talk called The Power of Metaphor and it’s absolutely brilliant. It covers the monomyth (the hero’s journey) and Jungian archetypes, illustrated with the examples Star Wars, The Dark Knight, and Jurassic Park.

At Clearleft, I’m planning to reprise the workshop I did a few years ago about narrative structure—very handy for anyone preparing a conference talk, blog post, case study, or anything really:

Ellen and I have been enjoying some great philosophical discussions about exactly what a story is, and how does it differ from a narrative structure, or a plot. I really love Ellen’s working definition: Narrative. In Space. Over Time.

This led me to think that there’s a lot that we can borrow from the world of storytelling—films, novels, fairy tales—not necessarily about the stories themselves, but the kind of narrative structures we could use to tell those stories. After all, the story itself is often the same one that’s been told time and time again—The Hero’s Journey, or some variation thereof.

I realised that Mike’s monomyth talk aligns nicely with my workshop. So I decided to prep my fellow Clearlefties for the workshop with a movie night.

Popcorn was popped, pizza was ordered, and comfy chairs were suitably arranged. Then we watched Mike’s talk. Everyone loved it. Then it was decision time. Which of three films covered in the talk would we watch? We put it to a vote.

It came out as an equal tie between Jurassic Park and The Dark Knight. How would we resolve this? A coin toss!

The toss went to The Dark Knight. In retrospect, a coin toss was a supremely fitting way to decide to watch that film.

It was fun to watch it again, particularly through the lens of Mike’s analyis of its Jungian archetypes.

But I still think the film is about game theory.

Wednesday, July 3rd, 2019

You are not connected to the Internet

This is a very cute offline page. Ali Spittel has written up how it was made too.

Tuesday, July 2nd, 2019

The trimCache function in Going Offline …again

It seems that some code that I wrote in Going Offline is haunted. It’s the trimCache function.

First, there was the issue of a typo. Or maybe it’s more of a brainfart than a typo, but either way, there’s a mistake in the syntax that was published in the book.

Now it turns out that there’s also a problem with my logic.

To recap, this is a function that takes two arguments: the name of a cache, and the maximum number of items that cache should hold.

function trimCache(cacheName, maxItems) {

First, we open up the cache:

caches.open(cacheName)
.then( cache => {

Then, we get the items (keys) in that cache:

cache.keys()
.then(keys => {

Now we compare the number of items (keys.length) to the maximum number of items allowed:

if (keys.length > maxItems) {

If there are too many items, delete the first item in the cache—that should be the oldest item:

cache.delete(keys[0])

And then run the function again:

.then(
    trimCache(cacheName, maxItems)
);

A-ha! See the problem?

Neither did I.

It turns out that, even though I’m using then, the function will be invoked immediately, instead of waiting until the first item has been deleted.

Trys helped me understand what was going on by making a useful analogy. You know when you use setTimeout, you can’t put a function—complete with parentheses—as the first argument?

window.setTimeout(doSomething(someValue), 1000);

In that example, doSomething(someValue) will be invoked immediately—not after 1000 milliseconds. Instead, you need to create an anonymous function like this:

window.setTimeout( function() {
    doSomething(someValue)
}, 1000);

Well, it’s the same in my trimCache function. Instead of this:

cache.delete(keys[0])
.then(
    trimCache(cacheName, maxItems)
);

I need to do this:

cache.delete(keys[0])
.then( function() {
    trimCache(cacheName, maxItems)
});

Or, if you prefer the more modern arrow function syntax:

cache.delete(keys[0])
.then( () => {
    trimCache(cacheName, maxItems)
});

Either way, I have to wrap the recursive function call in an anonymous function.

Here’s a gist with the updated trimCache function.

What’s annoying is that this mistake wasn’t throwing an error. Instead, it was causing a performance problem. I’m using this pattern right here on my own site, and whenever my cache of pages or images gets too big, the trimCaches function would get called …and then wouldn’t stop running.

I’m very glad that—witht the help of Trys at last week’s Homebrew Website Club Brighton—I was finally able to get to the bottom of this. If you’re using the trimCache function in your service worker, please update the code accordingly.

Management regrets the error.

Design is a (hard) job. | Zeldman on Web & Interaction Design

It me:

Writing comes naturally to me when I’m expressing myself on my own site, with no outside assignment and no deadline except my own sense of urgency about an idea. It’s easy when I’m crafting a brief text message or tweet. Or a letter to a friend.

But give me a writing assignment and a deadline, and I’m stuck. Paralysis, avoidance, a dissatisfaction with myself and the assignment—all the usual hobgoblins spring immediately to life.

Monday, July 1st, 2019

Why Did I Have Difficulty Learning React? - Snook.ca

When people talk about learning React, I think that React, in and of itself, is relatively easy to understand. At least, I felt it was. I have components. I have JSX. I hit some hiccups with required keys or making sure I was wrapping child elements properly. But overall, I felt like I grasped it well enough.

Throw in everything else at the same time, though, and things get confusing because it’s hard at first to recognize what belongs to what. “Oh, this is Redux. That is React. That other thing is lodash. Got it.”

This resonates a lot with Dave’s post:

React is an ecosystem. I feel like it’s a disservice to anyone trying to learn to diminish all that React entails. React shows up on the scene with Babel, Webpack, and JSX (which each have their own learning curve) then quickly branches out into technologies like Redux, React-Router, Immutable.js, Axios, Jest, Next.js, Create-React-App, GraphQL, and whatever weird plugin you need for your app.

Sunday, June 30th, 2019

Get off of Twitter | Read the Tea Leaves

You can’t criticize Twitter on Twitter. It just doesn’t work. The medium is the message.

Nolan’s plea for sanity.

Write blog posts. Use RSS. Use micro.blog. Use Mastodon. Use Pleroma. Use whatever you want, as long as it isn’t manipulating you with algorithms or selling access to your data to advertisers.