ENTRIES TAGGED "html"

It’s time for a web page diet

Site speed is essential to business success, yet many pages are getting bigger and slower.

Illustration of scaleEarlier this year, I was researching online consumer preferences for a client and discovered, somewhat unsurprisingly, that people expect web sites to be fast and responsive, particularly when they’re shopping. What did surprised me, however, were findings in Radware’s “State of the Union Report Spring 2014” (registration required) that showed web sites, on average, were becoming bigger in bytes and slower in response time every year. In fact, the average Alexa 1000 web page has grown from around 780KB and 86 resources in 2011 to more than 1.4MB and 99 resources by the time of the early “2014 State of the Union Winter Report.”

As an experiment, I measured the resources loaded for Amazon.com on my own computer: 2.6MB loaded with 252 requests!

This seemed so odd. Faster is more profitable, yet companies were actually building fatter and slower web sites. What was behind all these bytes? Had web development become so sophisticated that all the technology would bust the seams of the browser window? Read more…

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What it really means when people say “Everything in JavaScript is an object”

A new mantra for your next (programming) meditation session.

When you begin programming with JavaScript you might run across books, tutorials, and people who say “Everything in JavaScript is an object.” While it’s not 100% true (not *everything* is an object), it is *mostly* true. And sometimes this can be a bit surprising.

For instance, to most people functions and objects look and act completely different. And in many languages, functions and objects *are* completely different. However, in JavaScript, a function is an object. This can take a bit of concentrated attention to get your head around, but it’s an important concept because it’s the secret behind another big topic in JavaScript: functions as first class values.

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It’s the end of the web as we knew it

You might feel fine.

For the past 15 years, Google has enforced the classic “HTML as foundation” architecture at the heart of the Web. Content creators and the developers who support them had to present content and link information as part of their pages’ HTML if they wanted Google’s spidering bots to see them. Google effectively punished developers who made links or content available only through JavaScript (or images, or CSS), giving them low or non-existent search results.

Google did this to keep their processing simple, not because of a deep fondness for HTML. Even as Google’s bots stuck to a simple diet of HTML, other parts of Google were developing JavaScript-centric approaches, like AngularJS: a “Superheroic JavaScript MVW Framework” that “is what HTML would have been, had it been designed for building web-apps.”

Angular is far from alone. As JavaScript grew, more and more programmers wanted to build their apps as programs, not as pages. Or, as Jen Simmons summarized it at Fluent, “Dang that stupid HTML, I’m just going to load an empty page… then I’ll run the real program, I’ll run the JavaScript.” Read more…

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Dos and don’ts in JavaScript

A few best practices for when you're learning the language

With every programming language, there’s a list of do’s and don’ts and JavaScript is no exception. Some of these best practices are there for your protection (like always always always using semi-colons!); some to make your code more readable and less error-prone; and some to increase the efficiency of your code. Read more…

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I just slipped on a banana peel named “this”

Keeping track of this in your JavaScript code

In JavaScript, the special variable this is used to refer an object. But which object this refers too depends on the code you’re executing and how this is used. So, a common problem for those learning JavaScript is keeping track of the value of this in different situations. You can be happily testing your code, and then – bam! Suddenly, things stop working, and you’re wondering what happened, not realizing that you’re assuming this is set to one value, when in fact, it’s an entirely different value. And, bugs caused by confusion about this are notoriously difficult to track down.
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What is that upside-down tree doing in my browser?

Start using JavaScript to create dynamic web pages by updating the DOM.

The secret to getting your web pages to do your bidding with code is to use JavaScript to manipulate the Document Object Model, or DOM. The DOM is an upside-down tree-like structure that the browser uses to represent your web page internally, and it’s by getting and setting values in the DOM that you can modify your web page in response to users doing things like clicking a button, moving the mouse, or dragging an element around.

Getting started with the DOM is easy once you understand how the browser translates your HTML into this internal structure made of objects. Once these objects are created, then you can manipulate them using a wide variety of properties and methods, to change the content of an element, to add a style to an element, or even remove an element from the page completely.

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Wait, where is my variable defined?

Learn JavaScript scope so you always know where your variables are defined

You may have noticed that Head First JavaScript Programming is released! Now that the book is done, we’ve got a few more Head First JavaScript Programming teasers for you. The book is aimed at those of you who are learning JavaScript from the ground up, and our goal with these teasers is to tease out a few characteristics of the language that might surprise you, trip you up, or that you might want to pay special attention to as you learn.

Whether you’re coming to JavaScript from another language, or you’re learning JavaScript as your first language, the way scope works — that is, when and where your variables are defined — might surprise you. Scope in JavaScript isn’t always intuitive, and it’s easy to make some simple mistakes that can cause your code to work in unexpected ways.

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Can we extend the web cleanly?

The DOM and human nature create some challenges

“Design by Committee” is rarely a compliment. Can the Web shift away from that model, retaining some order without falling into troublesome chaos?

The Manifesto

Part of the excitement around the Extensible Web Manifesto was that it wanted to move the Web to more of an evolutionary model:

We aim to tighten the feedback loop between the editors of web standards and web developers.

Today, most new features require months or years of standardization, followed by careful implementation by browser vendors, only then followed by developer feedback and iteration. We prefer to enable feature development and iteration in JavaScript, followed by implementation in browsers and standardization.

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The power of HTML

Acknowledging the source of the Web's strength

For a growing number of developers, “web” means “JavaScript”. Programmers like to focus on programming languages, but the Web’s basic power comes from its support for communications, not programming.

I asked Jen Simmons, host of the Web Ahead podcast, to keynote Fluent after seeing her give a talk on responsive layouts at the ARTIFACT conference last year. It wasn’t just a great talk on responsive layout, but an exploration of the Web foundations that make responsive layout possible. Responsive layout’s foundations are deep in HTML, which contained those multi-device values from the beginning.

At Fluent, Simmons delivered A Love Letter to HTML, exploring HTML’s origins. The goals driving a memo written 25 years ago gave the Web strengths that developers need to study today.

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Transforming the web (through transformation)

Decorating content may no longer be enough

Photo: http://commons.wikimedia.org/wiki/File:Metamorphosis_frog_Meyers.pngThousands of people invented it independently. Millions use it without thinking about a broader context. It’s time to name it so we can talk about it.

Transformation is changing the way we look at the balance between clients and servers, our approach to formatting and layout, and our expectations of what’s possible on the Web. As applications shift from transformation on the server toward transformation on arrival on the client, transformation’s central role becomes more visible.

“Templating” doesn’t quite capture what’s happening here. While templates are often a key tool, describing that tool doesn’t explain the shift from server to client. Templating also misses the many cases where developers are using plain JavaScript to insert, delete, and modify the document tree in response to incoming data.

These practices have been emerging for a long time, in many different guises:

  • In the Dynamic HTML days, scripts might tinker with the DOM tree as well as modify CSS presentation.
  • Transformation was supposed to be a regular and constant thing in the early XSLT plans. Stylesheets on the client would generate presentation from clean blocks of XML content.
  • Ajax opened the door to shell pages, apps that set up a UI, but get most of their content elsewhere, using JavaScript to put it in place.
  • New data format options evolved at about the same time that Ajax emerged. JSON offered a more concise set of programmer-friendly content tools. Many apps include a ‘bind JSON to HTML before showing it to the user’ step.
  • Template systems now run on the client as well as the server. In many systems, templates on the server feed data to the client, which applies other templates to that data before presenting it to users.
  • The HTTP powering Ajax still created a long slow cycle of interaction. WebSockets and WebRTC now offer additional approaches for collecting content with less overhead, making it easier to create many more small transformations.
  • Some developers and designers have long thought of the document tree as a malleable collection of layout boxes rather than a deliberately coherent base layer. Separation of concerns? A dead horse, apparently. Recent debates over CSS Regions highlighted these issues again.

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