Jeremy Keith

Jeremy Keith

Making websites. Writing books. Speaking at events. Living in Brighton. Working at Clearleft. Playing music. Taking photos. Answering email.

Journal 2485 sparkline Links 7493 sparkline Articles 70 sparkline Notes 3804 sparkline

Monday, June 18th, 2018

My biggest challenge with JavaScript | Go Make Things

This really, really resonates with me:

I think the thing I struggle the most with right now is determining when something new is going to change the way our industry works for the better (like responsive web design did 5 or 6 years ago), and when it’s just a fad that will fade away in a year or three (which is how I feel about our obsession with things like Angular and React).

I try to avoid jumping from fad to fad, but I also don’t want to be that old guy who misses out on something that’s an important leap forward for us. I spend a lot of time thinking about the longer term impact of the things we make (and make with).

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.

Checked in at The Burren. Sunday session — with Jessica map

Checked in at The Burren. Sunday session — with Jessica

Saturday, June 16th, 2018

On Rejection | Zeldman on Web & Interaction Design

The focus of the A Book Apart series is what makes it great …and that means having to reject some proposals that don’t fit. Even though I’ve had the honour of being a twice-published A Book Apart author, I also have the honour of receiving a rejection, which Jeffrey mentions here:

In one case we even had to say no to a beautifully written, fully finished book.

That was Resilient Web Design.

So why did we turn down books we knew would sell? Because, again—they weren’t quite right for us.

It was the right decision. And this is the right advice:

If you’ve sent us a proposal that ultimately wasn’t for us, don’t be afraid to try again if you write something new—and most importantly, believe in yourself and keep writing.

Friday, June 15th, 2018

Thursday, June 14th, 2018

Wednesday, June 13th, 2018

Tuesday, June 12th, 2018

Any Site can be a Progressive Web App - Jeremy Keith | DeltaV 2018 - YouTube

Here’s a really quick (ten minute) talk about the offline user experience that I gave at the Delta V conference recently. I’m quite happy with how it turned out—there’s something to be said for having a short and snappy time slot.

There’s a common misconception that making a Progressive Web App means creating a Single Page App with an app-shell architecture. But the truth is that literally any website can benefit from the performance boost that results from the combination of HTTPS + Service Worker + Web App Manifest.

Any Site can be a Progressive Web App - Jeremy Keith | DeltaV 2018

Password Tips From a Pen Tester: Common Patterns Exposed

I’ve been wondering about this for quite a while: surely demanding specific patterns in a password (e.g. can’t be all lowercase, must include at least one number, etc.) makes it easier to crack them, right? I mean, you’re basically providing a ruleset for brute-forcing.

Turns out, yes. That’s exactly right.

When employees are faced with this requirement, they tend to:

  • Choose a dictionary word or a name
  • Make the first character uppercase
  • Add a number at the end, and/or an exclamation point

If we know that is a common pattern, then we know where to start…

Resilient, Declarative, Contextual

This is really good breakdown of what’s different about CSS (compared to other languages).

These differences may feel foreign, but it’s these differences that make CSS so powerful. And it’s my suspicion that developers who embrace these things, and have fully internalized them, tend to be far more proficient in CSS.