Tags: html5

261

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Wednesday, August 26th, 2020

Submitting a form with datalist

I’m a big fan of HTML5’s datalist element and its elegant design. It’s a way to progressively enhance any input element into a combobox.

You use the list attribute on the input element to point to the ID of the associated datalist element.

<label for="homeworld">Your home planet</label>
<input type="text" name="homeworld" id="homeworld" list="planets">
<datalist id="planets">
 <option value="Mercury">
 <option value="Venus">
 <option value="Earth">
 <option value="Mars">
 <option value="Jupiter">
 <option value="Saturn">
 <option value="Uranus">
 <option value="Neptune">
</datalist>

It even works on input type="color", which is pretty cool!

The most common use case is as an autocomplete widget. That’s how I’m using it over on The Session, where the datalist is updated via Ajax every time the input is updated.

But let’s stick with a simple example, like the list of planets above. Suppose the user types “jup” …the datalist will show “Jupiter” as an option. The user can click on that option to automatically complete their input.

It would be handy if you could automatically submit the form when the user chooses a datalist option like this.

Well, tough luck.

The datalist element emits no events. There’s no way of telling if it has been clicked. This is something I’ve been trying to find a workaround for.

I got my hopes up when I read Amber’s excellent article about document.activeElement. But no, the focus stays on the input when the user clicks on an option in a datalist.

So if I can’t detect whether a datalist has been used, this best I can do is try to infer it. I know it’s not exactly the same thing, and it won’t be as reliable as true detection, but here’s my logic:

  • Keep track of the character count in the input element.
  • Every time the input is updated in any way, check the current character count against the last character count.
  • If the difference is greater than one, something interesting happened! Maybe the user pasted a value in …or maybe they used the datalist.
  • Loop through each of the options in the datalist.
  • If there’s an exact match with the current value of the input element, chances are the user chose that option from the datalist.
  • So submit the form!

Here’s how that translates into DOM scripting code:

document.querySelectorAll('input[list]').forEach( function (formfield) {
  var datalist = document.getElementById(formfield.getAttribute('list'));
  var lastlength = formfield.value.length;
  var checkInputValue = function (inputValue) {
    if (inputValue.length - lastlength > 1) {
      datalist.querySelectorAll('option').forEach( function (item) {
        if (item.value === inputValue) {
          formfield.form.submit();
        }
      });
    }
    lastlength = inputValue.length;
  };
  formfield.addEventListener('input', function () {
    checkInputValue(this.value);
  }, false);
});

I’ve made a gist with some added feature detection and mustard-cutting at the start. You should be able to drop it into just about any page that’s using datalist. It works even if the options in the datalist are dynamically updated, like the example on The Session.

It’s not foolproof. The inference relies on the difference between what was previously typed and what’s autocompleted to be more than one character. So in the planets example, if someone has type “Jupite” and then they choose “Jupiter” from the datalist, the form won’t automatically submit.

But still, I reckon it covers most common use cases. And like the datalist element itself, you can consider this functionality a progressive enhancement.

Monday, May 4th, 2020

A decade apart

Today marks ten years since the publication of HTML5 For Web Designers, the very first book from A Book Apart.

I’m so proud of that book, and so honoured that I was the first author published by the web’s finest purveyors of brief books. I mean, just look at the calibre of their output since my stumbling start!

Here’s what I wrote ten years ago.

Here’s what Jason wrote ten years ago.

Here’s what Mandy wrote ten years ago.

Here’s what Jeffrey wrote ten years ago.

They started something magnificent. Ten years on, with Katel at the helm, it’s going from strength to strength.

Happy birthday, little book! And happy birthday, A Book Apart! Here’s to another decade!

A Book Apart authors, 1-6

Friday, March 20th, 2020

What Does `playsinline` Mean in Web Video? | CSS-Tricks

I have to admit, I don’t think I even knew of the existence of the playsinline attribute on the video element. Here, Chris runs through all the attributes you can put in there.

Saturday, December 29th, 2018

The 100 Year Web (In Praise of XML)

I don’t agree with Steven Pemberton on a lot of things—I’m not a fan of many of the Semantic Web technologies he likes, and I think that the Robustness Principle is well-suited to the web—but I always pay attention to what he has to say. I certainly share his concern that migrating everything to JavaScript is not good for interoperability:

This is why there are so few new elements in HTML5: they haven’t done any design, and instead said “if you need anything, you can always do it in Javascript”.

And they all have.

And they are all different.

Read this talk transcript, and even if you don’t agree with everything in it today, you may end up coming back to it in the future. He’s playing the long game:

The web is the way now that we distribute information. We will need the web pages we create now to be readable in 100 years time, just as we can still read 100-year-old books.

Requiring a webpage to depend on a particular 100-year-old implementation of Javascript is not exactly evidence of future-thinking.

Sunday, May 6th, 2018

HTML5 Constraint Validation

The slides from a presentation by Drew on all the functionality that browsers give us for free when it comes to validating form inputs.

Half the battle of the web platform is knowing what technology is out there, ready to use. We’re all familiar with the ability to declare validation constraints in our HTML5 forms, but were you aware there’s a JavaScript API that goes along with it?

Friday, April 20th, 2018

Timing

Apple Inc. is my accidental marketing department.

On April 29th, 2010, Steve Jobs published his infamous Thoughts on Flash. It thrust the thitherto geek phrase “HTML5” into the mainstream press:

HTML5, the new web standard that has been adopted by Apple, Google and many others, lets web developers create advanced graphics, typography, animations and transitions without relying on third party browser plug-ins (like Flash). HTML5 is completely open and controlled by a standards committee, of which Apple is a member.

Five days later, I announced the first title from A Book Apart: HTML5 For Web Designers. The timing was purely coincidental, but it definitely didn’t hurt that book’s circulation.

Fast forward eight years…

On March 29th, 2018, Apple released the latest version of iOS. Unmentioned in the press release, this update added service worker support to Mobile Safari.

Five days later, I announced the 26th title from A Book Apart: Going Offline.

For a while now, quite a few people have cited Apple’s lack of support as a reason why they weren’t investigating service workers. That excuse no longer holds water.

Once again, the timing is purely coincidental. But it can’t hurt.

Monday, November 20th, 2017

Happier HTML5 Form Validation - daverupert.com

Dave uses just a smidgen of JavaScript to whip HTML5’s native form validation into shape.

Instead of being prescriptive about error messaging, we use what the browser natively gives us.

Wednesday, July 26th, 2017

Bruce Lawson’s personal site  : Eulogy for Flash

Web developers aren’t going to shed many tears for Flash, but as Bruce rightly points out, it led the way for many standards that followed. Flash was the kick up the arse that the web needed.

He also brings up this very important question:

I’m also nervous; one of the central tenets of HTML is to be backwards-compatible and not to break the web. It would be a huge loss if millions of Flash movies become unplayable. How can we preserve this part of our digital heritage?

This is true of the extinction of any format. Perhaps this is an opportunity for us to tackle this problem head on.

Sunday, June 25th, 2017

Implementing a slider well

A look at the feedback needed for a slider control that feels “right”.

You can get most of the behavioural (though not styling) suggestions in HTML by doing this:

<form>
  <input type="range" min="0" max="100" value="50"
   onchange="amount.value=this.value"
   onmousemove="amount.value=this.value">
  <output name="amount">50</output>
</form>

Thursday, January 19th, 2017

Making input type=date complicated – Samsung Internet Developers – Medium

PPK has posted some excellent thinking on calendar widgets to Ev’s blog.

Wednesday, August 31st, 2016

I Wanted To Type a Number | Filament Group, Inc., Boston, MA

Choosing the right input type for your form field.

Tuesday, May 3rd, 2016

HTML5 accessibility

A glanceable one-stop-shop for how today’s browsers are dealing with today’s accessibility features. Then you can dive deeper into each one.

Sunday, April 24th, 2016

Conversational interfaces

Psst… Jeremy! Right now you’re getting notified every time something is posted to Slack. That’s great at first, but now that activity is increasing you’ll probably prefer dialing that down.

Slackbot, 2015

What’s happening?

Twitter, 2009

Why does everyone always look at me? I know I’m a chalkboard and that’s my job, I just wish people would ask before staring at me. Sometimes I don’t have anything to say.

Existentialist chalkboard, 2007

I’m Little MOO - the bit of software that will be managing your order with us. It will shortly be sent to Big MOO, our print machine who will print it for you in the next few days. I’ll let you know when it’s done and on it’s way to you.

Little MOO, 2006

It looks like you’re writing a letter.

Clippy, 1997

Your quest is to find the Warlock’s treasure, hidden deep within a dungeon populated with a multitude of terrifying monsters. You will need courage, determination and a fair amount of luck if you are to survive all the traps and battles, and reach your goal — the innermost chambers of the Warlock’s domain.

The Warlock Of Firetop Mountain, 1982

Welcome to Adventure!! Would you like instructions?

Colossal Cave, 1976

I am a lead pencil—the ordinary wooden pencil familiar to all boys and girls and adults who can read and write.

I, Pencil, 1958

ÆLFRED MECH HET GEWYRCAN
Ælfred ordered me to be made

Ashmolean Museum, Oxford

The Ælfred Jewel, ~880

Technical note

I have marked up the protagonist of each conversation using the cite element. There is a long-running dispute over the use of this element. In HTML 4.01 it was perfectly fine to use cite to mark up a person being quoted. In the HTML Living Standard, usage has been narrowed:

The cite element represents the title of a work (e.g. a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, a computer program, etc). This can be a work that is being quoted or referenced in detail (i.e. a citation), or it can just be a work that is mentioned in passing.

A person’s name is not the title of a work — even if people call that person a piece of work — and the element must therefore not be used to mark up people’s names.

I disagree.

In the examples above, it’s pretty clear that I, Pencil and Warlock Of Firetop Mountain are valid use cases for the cite element according to the HTML5 definition; they are titles of works. But what about Clippy or Little Moo or Slackbot? They’re not people …but they’re not exactly titles of works either.

If I were to mark up a dialogue between Eliza and a human being, should I only mark up Eliza’s remarks with cite? In text transcripts of conversations with Alexa, Siri, or Cortana, should only their side of the conversation get attributed as a source? Or should they also be written without the cite element because it must not be used to mark up people’s names …even though they are not people, according to conventional definition.

It’s downright botist.

Friday, April 1st, 2016

simpl.info

This is a very handy resource—a collection of minimum viable implementations of HTML5 features and JavaScript APIs.

Sunday, March 13th, 2016

Instagram-style filters in HTML5 Canvas | Viget

Una’s [Instagram filters in CSS}(https://github.com/una/CSSgram) are great, but the browser support for CSS filters isn’t as good as, say, the browser support for canvas. Here’s a clever bit of scripting to polyfill filters using canvas.

Friday, February 19th, 2016

New edition

Six years ago I wrote a book and the brand new plucky upstart A Book Apart published it.

Six years! That’s like a geological age in internet years.

People liked the book. That’s very gratifying. I’m quite proud of it, and it always gives me a warm glow when someone tells me they enjoyed reading it.

Jeffrey asked me a while back about updating the book for a second edition—after all, six years is crazy long time for a web book to be around. I said no, because I just wouldn’t have the time, but mostly because—as the old proverb goes—you can step in the same river twice. Proud as I am of HTML5 For Web Designers, I consider it part of my past.

“What about having someone else update it?” Well, that made me nervous. I feel quite protective of my six year old.

“What about Rachel Andrew?” Ah, well, that’s a different story! Absolutely—if there’s one person I trust to bring the up to date, it’s Rachel.

She’s done a fine, fine job. The second edition of HTML5 For Web Designers is now available.

I know what you’re going to ask: how much difference is there between the two editions? Well, in the introduction to the new edition, I’m very pleased to say that Rachel has written:

I’ve been struck by how much has remained unchanged in that time.

There’s a new section on responsive images. That’s probably the biggest change. The section on video has been expanded to include captioning. There are some updates and tweaks to the semantics of some of the structural elements. So it’s not a completely different book; it’s very much an update rather than a rewrite.

If you don’t have a copy of HTML5 For Web Designers and you’ve been thinking that maybe it’s too out-of-date to bother with, rest assured that it is now bang up to date thanks to Rachel.

Jeffrey has written a lovely new foreword for the second edition:

HTML5 for Web Designers is a book about HTML like Elements of Style is a book about commas. It’s a book founded on solid design principles, and forged at the cutting edge of twenty-first century multi-device design and development.

Monday, February 1st, 2016

A simple HTML5 Progress bar | Charlotte Jackson, Front-end developer

I love this little markup pattern: simple, accessible and elegant …with some quirky CSS gotchas around styling non-standard prefixed pseudo-elements. They came from the Shadow DOM …dun dun DUN!

Friday, November 27th, 2015

HTML5: The New Flash

A new presentation from the wonderfully curmudgeonly Steven Pemberton, the Nosferatu of the web. Ignore the clickbaity title.

I don’t agree with everything he says here, but I strongly agree with his preference for declarative solutions over (or as well as) procedural ones. In short: don’t make JavaScript for something that could be handled in markup.

This part really, really resonated with me:

The web is the way now that we distribute information. We will need the web pages we create now to be readable in 100 years time, just as we can still read 100-year-old books.

Requiring a webpage to depend on a particular 100-year-old implementation of Javascript is not exactly evidence of future-thinking.

Friday, March 27th, 2015

isolani - Web Standards: Flash’s slide into irrelevance

Mike runs through the history of Flash. Those who forget the history of the web are doomed to repeat it:

The struggle now seems to be turning to native apps versus non-native apps on the mobile platform. It is similar to Flash’s original battle ground: the argument that the Web technology stack is not suitable for building applications with a polished user-experience.

Sunday, December 21st, 2014

HTML5 Differences from HTML4

I just noticed that I’m mentioned in the acknowledgements of this most handy of W3C documents. This pleases me disproportionately.