Tags: scripting

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Thursday, February 16th, 2017

Teaching in Porto, day three

Day two ended with a bit of a cliffhanger as I had the students mark up a document, but not yet style it. In the morning of day three, the styling began.

Rather than just treat “styling” as one big monolithic task, I broke it down into typography, colour, negative space, and so on. We time-boxed each one of those parts of the visual design. So everyone got, say, fifteen minutes to write styles relating to font families and sizes, then another fifteen minutes to write styles for colours and background colours. Bit by bit, the styles were layered on.

When it came to layout, we closed the laptops and returned to paper. Everyone did a quick round of 6-up sketching so that there was plenty of fast iteration on layout ideas. That was followed by some critique and dot-voting of the sketches.

Rather than diving into the CSS for layout—which can get quite complex—I instead walked through the approach for layout; namely putting all your layout styles inside media queries. To explain media queries, I first explained media types and then introduced the query part.

I felt pretty confident that I could skip over the nitty-gritty of media queries and cross-device layout because the next masterclass that will be taught at the New Digital School will be a week of responsive design, taught by Vitaly. I just gave them a taster—Vitaly can dive deeper.

By lunch time, I felt that we had covered CSS pretty well. After lunch it was time for the really challenging part: JavaScript.

The reason why I think JavaScript is challenging is that it’s inherently more complex than HTML or CSS. Those are declarative languages with fairly basic concepts at heart (elements, attributes, selectors, etc.), whereas an imperative language like JavaScript means entering the territory of logic, loops, variables, arrays, objects, and so on. I really didn’t want to get stuck in the weeds with that stuff.

I focused on the combination of JavaScript and the Document Object Model as a way of manipulating the HTML and CSS that’s already inside a browser. A lot of that boils down to this pattern:

When (some event happens), then (take this action).

We brainstormed some examples of this e.g. “When the user submits a form, then show a modal dialogue with an acknowledgement.” I then encouraged them to write a script …but I don’t mean a script in the JavaScript sense; I mean a script in the screenwriting or theatre sense. Line by line, write out each step that you want to accomplish. Once you’ve done that, translate each line of your English (or Portuguese) script into JavaScript.

I did quick demo as a proof of concept (which, much to my surprise, actually worked first time), but I was at pains to point out that they didn’t need to remember the syntax or vocabulary of the script; it was much more important to have a clear understanding of the thinking behind it.

With the remaining time left in the day, we ran through the many browser APIs available to JavaScript, from the relatively simple—like querySelector and Ajax—right up to the latest device APIs. I think I got the message across that, using JavaScript, there’s practically no limit to what you can do on the web these days …but the trick is to use that power responsibly.

At this point, we’ve had three days and we’ve covered three layers of web technologies: HTML, CSS, and JavaScript. Tomorrow we’ll take a step back from the nitty-gritty of the code. It’s going to be all about how to plan and think about building for the web before a single line of code gets written.

Friday, November 25th, 2016

Hey designers, if you only know one thing about JavaScript, this is what I would recommend | CSS-Tricks

This is a really great short explanation by Chris. I think it shows that the really power of JavaScript in the browser isn’t so much the language itself, but the DOM—the glue that ties the JavaScript to the HTML.

It reminds me of the old jQuery philosophy: find something and do stuff to it.

Wednesday, June 29th, 2016

Things to Know (and Potential Dangers) with Third-Party Scripts | CSS-Tricks

Third-party scripts can provide powerful functionality, but they also bring risks to privacy, security, performance, and page behavior.

Monday, March 7th, 2016

A Year Without jQuery

In many ways, moving to vanilla JavaScript highlights the ugliness of working with the DOM directly, and the shortcomings of native Element object — shortcomings which Resig solved so incredibly eloquently with the jQuery API.

Having said that, the lessons I’ve learned over the last year have made me a better developer, and the tools built in the process have opened my eyes and given me enough confidence and understanding of vanilla JavaScript that the only scenario where I would personally consider using jQuery again would be a project needing IE8 support.

Sunday, November 15th, 2015

An Offline Experience with Service Workers | Brandon Rozek

A great walkthrough of setting up a Service Worker for a blog. The code is here but more importantly, as Brandon says:

I wouldn’t be able to implement this myself if it wasn’t for some of the awesome people I mentioned earlier sharing their experience. So share, share, share!

Monday, April 13th, 2015

Progressive enhancement with handlers and enhancers | hiddedevries.nl

I like this declarative approach to associating JavaScript behaviours with HTML elements.

Thursday, March 12th, 2015

A JS framework on every table - Allen Pike

The Tower of JavaScript Babel.

Wednesday, February 18th, 2015

Making the case for Progressive Javascript — The Millstone — Medium

I think we can all agree that “isomorphic JavaScript” is a terrible name for a good idea. I quite like calling it “portable JavaScript”, but here’s a good case for calling it “progressive JavaScript.”

(Right up until the end when the author says “But mainly, it’s pretty safe to assume JavaScript will just work. Everywhere.” …which is precisely the kind of unfounded assumption that leads to the very problems that isomorphic/portable/progressive JavaScript can help fix.)

Wednesday, December 17th, 2014

You Don’t Need jQuery! – Free yourself from the chains of jQuery by embracing and understanding the modern Web API and discovering various directed libraries to help you fill in the gaps.

The tone is a bit too heavy-handed for my taste, but the code examples here are very handy if you’re weaning yourself off jQuery.

Wednesday, September 24th, 2014

Using ServiceWorker in Chrome today - JakeArchibald.com

It’s very early days for ServiceWorker, but Jake is on hand with documentation and instructions on its use. To be honest, most of this is over my head and I suspect it won’t really “click” until I try using it for myself.

Where it gets really interesting is in the comments. Stuart asks “What about progressive enhancement?” And Jake points out that because a ServiceWorker won’t be installed on a first visit, you pretty much have to treat it as an enhancement. In fact, you’d have to go out of your way to make it a requirement:

You could, of course, throw up a splash screen and wait for the ServiceWorker to install, creating a ServiceWorker-dependant experience. I will hunt those people down.

Tuesday, July 1st, 2014

Learn JavaScript & jQuery - a book about interactive front-end web development

This looks like it could be a great book for anyone looking to get starting with JavaScript.

Wednesday, June 11th, 2014

Comparing two ways to load non-critical CSS

Scott’s trying to find out the best ways to load critical CSS first and non-critical CSS later. Good discussion ensues.

Friday, March 7th, 2014

Making progress

When I was talking about Async, Ajax, and animation, I mentioned the little trick I’ve used of generating a progress element to indicate to the user that an Ajax request is underway.

I sometimes use the same technique even if Ajax isn’t involved. When a form is being submitted, I find it’s often good to provide explicit, immediate feedback that the submission is underway. Sure, the browser will do its own thing but a browser doesn’t differentiate between showing that a regular link has been clicked, and showing that all those important details you just entered into a form are on their way.

Here’s the JavaScript I use. It’s fairly simplistic, and I’m limiting it to POST requests only. At the moment that a form begins to submit, a progress element is inserted at the end of the form …which is usually right by the submit button that the user will have just pressed.

While I’m at it, I also set a variable to indicate that a POST submission is underway. So even if the user clicks on that submit button multiple times, only one request is set.

You’ll notice that I’m attaching an event to each form element, rather than using event delegation to listen for a click event on the parent document and then figuring out whether that click event was triggered by a submit button. Usually I’m a big fan of event delegation but in this case, it’s important that the event I’m listening to is the submit event. A form won’t fire that event unless the data is truly winging its way to the server. That means you can do all the client-side validation you want—making good use of the required attribute where appropriate—safe in the knowledge that the progess element won’t be generated until the form has passed its validation checks.

If you like this particular pattern, feel free to use the code. Better yet, improve upon it.

Sunday, March 2nd, 2014

Async, Ajax, and animation

I hadn’t been to one of Brighton’s Async JavaScript meetups for quite a while, but I made it along last week. Now that it’s taking place at 68 Middle Street, it’s a lot easier to get to …seeing as the Clearleft office is right upstairs.

James Da Costa gave a terrific presentation on something called Pjax. In related news, it turns out that the way I’ve been doing Ajax all along is apparently called Pjax.

Back when I wrote Bulletproof Ajax, I talked about using Hijax. The basic idea is:

  1. First, build an old-fashioned website that uses hyperlinks and forms to pass information to the server. The server returns whole new pages with each request.
  2. Now, use JavaScript to intercept those links and form submissions and pass the information via XMLHttpRequest instead. You can then select which parts of the page need to be updated instead of updating the whole page.

So basically your JavaScript is acting like a dumb waiter shuttling requests for page fragments back and forth between the browser and the server. But all the clever stuff is happening on the server, not the browser. To the end user, there’s no difference between that and a site that’s putting all the complexity in the browser.

In fact, the only time you’d really notice a difference is when something goes wrong: in the Hijax model, everything just falls back to full-page requests but keeps on working. That’s the big difference between this approach and the current vogue for “single page apps” that do everything in the browser—when something goes wrong there, the user gets bupkis.

Pjax introduces an extra piece of the puzzle—which didn’t exist when I wrote Bulletproof Ajax—and that’s pushState, part of HTML5’s History API, to keep the browser’s URL updated. Hence, pushState + Ajax = Pjax.

As you can imagine, I was nodding in vigourous agreement with everything James was demoing. It was refreshing to find that not everyone is going down the Ember/Angular route of relying entirely on JavaScript for core functionality. I was beginning to think that nobody cared about progressive enhancement any more, or that maybe I was missing something fundamental, but it turns out I’m not crazy after all: James’s demo showed how to write front-end code responsibly.

What was fascinating though, was hearing why people were choosing to develop using Pjax. It isn’t necessarily that they care about progressive enhancement, robustness, and universal access. Rather, it’s often driven by the desire to stay within the server-side development environment that they’re comfortable with. See, for example, DHH’s explanation of why 37 Signals is using this approach:

So you get all the advantages of speed and snappiness without the degraded development experience of doing everything on the client.

It sounds like they’re doing the right thing for the wrong reasons (a wrong reason being “JavaScript is icky!”).

A lot of James’s talk was focused on the user experience of the interfaces built with Hijax/Pjax/whatever. He had some terrific examples of how animation can make an enormous difference. That inspired me to do a little bit of tweaking to the Ajaxified/Hijaxified/Pjaxified portions of The Session.

Whenever you use Hijax to intercept a link, it’s now up to you to provide some sort of immediate feedback to the user that something is happening—normally the browser would take care of this (remember Netscape’s spinning lighthouse?)—but when you hijack that click, you’re basically saying “I’ll take care of this.” So you could, for example, display a spinning icon.

One little trick I’ve used is to insert an empty progress element.

Normally the progress element takes max and value attributes to show how far along something has progressed:

<progress max="100" value="75">75%</progress>

75%

But if you leave those out, then it’s an indeterminate progess bar:

<progress>loading...</progress>

loading…

The rendering of the progress bar will vary from browser to browser, and that’s just fine. Older browsers that don’t understand the progress will display whatever’s between the opening and closing tags.

Voila! You’ve got a nice lightweight animation to show that an Ajax request is underway.

Thursday, January 30th, 2014

You Might Not Need jQuery

A handy resource if you’re used to using jQuery for everything but you want to try going JavaScript commando.

Don’t get me wrong: jQuery is great, but for a lot of projects, you might not need 90% of the functionality it provides. So try starting with vanilla JS and only pulling in jQuery if and when you need it.

Thursday, January 16th, 2014

A Dive Into Plain JavaScript

A nice introduction to writing vanilla JavaScript, especially if you’re used to using jQuery.

Monday, December 9th, 2013

OriDomi - origami for the web

A fun little JavaScript library for folding the DOM like paper. The annotated source is really nicely documented.

Why I’m turning JavaScript off by default

Another good ol’ rant from Tom. It’s a bit extreme but the underlying lamentation with the abandonment of progressive enhancement is well founded.

Wednesday, September 25th, 2013

The ghost of browsers past

Even before a line of code was written for the line-mode browser simulator when we gathered together at CERN, there was a gleeful period of digital spelunking.

Brian goes browsing Demonstration data sources

We poked at the markup of the first ever website

  • What’s that NEXTID element? Turns it out it’s something specific to the NeXT operating system.
  • Why does the first iteration of HTML already contain H1 through to H6? It’s because they were lifted wholesale from a flavour of SGMLStandard Generalized Markup Language—that was already in use at CERN.

Oh, and Brian asked Robert Cailliau why they went with the term World Wide Web. “Well,” he said, “we had to call it something. And we thought we could always change it later.”

Then there was the story of the line-mode browser. It was created by Nicola Pellow, who was a student at CERN in 1990. She later worked on the Mac browser but her involvement with kickstarting the world wide web ended around 1993. She never showed up to any of the reunions.

We poked around in the (surprisingly short) source code of the line-mode browser. We found the lines that described how elements should be styled—the term “style sheet” appeared in a comment!

Proto-stylesheet Parsing the parser

If you’ve fired up the line-mode browser simulator and run some websites through it, you’ll probably see occasions where a whole bunch of JavaScript—nestled between script tags in the head of the document—gets rendered to the screen.

Clearleft

We could’ve hidden that JavaScript, but we made a deliberate decision to display it. That’s what the line-mode browser would have done. The script element didn’t exist back then. Heck, JavaScript didn’t exist back then. So browsers would have handled the unknown element in the standard HTML way: ignore the opening and closing tags and just render what’s in-between them. That’s still the error-handling model for unrecognised elements in HTML.

This is why we used to write our JavaScript like this:

<script language="JavaScript" type="text/javascript">
<!--
(JavaScript goes here)
//-->
</script>

The HTML comments stopped the JavaScript from being rendered to the screen in older browsers (like the line-mode browser). Using the opening HTML comment <!-- is functionally equivalent to // single-line comments in JavaScript …although you still need to prefix the closing --> comment with a //.

I remember doing this when I first started making websites in the 90s. You can see it if you view source on the first version of this website.

Later on, we all switched to XHTML so we updated the syntax to make it valid XML.

<script type="text/javascript">
//<![CDATA[
(JavaScript goes here)
//]]>
</script>

The <![CDATA[ part stops an XML parser from trying to parse the JavaScript. But HTML parsers would choke on that because it starts with an angle bracket. Hence the JavaScript-style // comment.

Anyway, we don’t bother with HTML or XHTML comments at the start of our script blocks anymore. And that’s why the line-mode browser simulator renders the JavaScript to the screen.

Note that the JavaScript isn’t executed. That’s thanks to a clever little hack by Remy: the line-mode browser simulator changes the type attribute of every script element to text/plain, effectively defusing them. Smart!

Friday, August 30th, 2013

Progressive Enhancement. Still Alive and Kickin’

Dan explains the reasoning behind his “Sigh, JavaScript” Tumblr blog, and provides an excellent example of progressive enhancement in the process.

Go, Dan, go!