barryvan

Archive for the ‘HTML’ category

Web developer tools

In this post, I’ll outline some of the web developer tools available in the major browsers: Firefox, Internet Explorer, Opera and Safari. This is a wholly subjective post, based on my experience as one of two developers on a very large AJAX application at Saron Education.

Firefox

Firefox has arguably got the best web development tools available, all of which can be downloaded from the Firefox Addons site. The two which I find most useful are the Web Developer Toolbar, by Chris Pederick, and the often-copied Firebug (official website), which itself sports a variety of addons.

Web Developer Toolbar

The web developer toolbar is useful for quickly enabling and disabling features of your site, checking CSS, emulating mobile browser rendering, and controlling Firefox more precisely. Personally, I find its most useful features are the ability to:

  • Disable the browser cache entirely, which removes the need for Control-Refresh or cache-clearing;
  • Outline deprecated elements, or any particular set of elements in a variety of fashions, which is very useful for updating old sites;
  • Extract colour information from the current website; and
  • View the cookie information for the current site.

Download the Web Developer Toolbar

Firebug

I sometimes wonder how I ever managed to develop web applications without Firebug. Firebug allows you to alter CSS styles on the fly, edit the HTML contents of the page on the fly, visually watch the DOM being changed by your scripts, debug your scripts, type and run JavaScript straight from the browser, visualise network activity, inspect XMLHttpRequests, and much much more besides. Firebug is, in my experience, the most mature, stable, and efficient of all the tools in this survey.

The features of Firebug which I find most useful are:

  • The ability to ‘inspect’ the DOM visually (by clicking on elements within the page), then alter their attributes, styles, and even their content dynamically;
  • The ability to watch the effects of DOM alterations by running scripts;
  • The console, with which you can craft and run JavaScript which is run as though it were part of the page itself;
  • The network monitor, which allows you to view all the POSTs and GETs your XMLHttpRequests create.

Download Firebug

Internet Explorer

Until IE 8, the tools available to developers in IE were woeful at best. Fortunately, however, Microsoft has got their act together, and mimicked Firebug for version 8. The features made available in this tool include

  • The ability to interrogate the DOM to view style information about elements (changing attributes and styles hardly ever seems to work in the latest Beta, so viewing them is all you can really achieve);
  • A console, with which you can craft and run Javascript as though it were embedded in the page;
  • Javascript debugging.

Unfortunately, these tools are still very much in beta, and are very buggy. As I mentioned, altering element attributes and styles hardly has any effect. Also, the CSS inspection system is poorly laid out and often just plain wrong. The console is well-implemented. The entire system is definitely a step in the right direction, but it suffers from bugs and lack of innovation. Also, it seems to slow down and destabilise the entire browser.

Internet Explorer 8′s developer tools are built in; access them with the F12 key.

Opera

Opera’s developer tools, codenamed ‘Dragonfly’, sit between Firebug and IE in terms of functionality and facility. The DOM inspection and manipulation tools work really well (as well as Firebug), and are more immediately configurable, thanks to a variety of toolbar buttons. Dragonfly doesn’t have a console; rather, it uses a ‘command line’ interface. The difference is that where the console in Firebug and IE has seperate areas for input and output (what you type and what it does), the command line mixes these two together, much like a Unix shell or DOS. Personally, I prefer the console paradigm, but it’s much of a muchness.

Opera’s Dragonfly is built in; access it by going to Tools -> Advanced -> Developer tools.

Safari

As with most Apple products, the developer tools in Safari are very pretty. There is a console akin to that in Firebug and IE, and you can inspect and manipulate the DOM. Unfortunately, however, the tools are quite buggy, and often fall down. Whilst the tools are very pretty, they don’t seem to be as stable even as IE 8′s.

Safari’s web developer tools are built in; access them enabling the develop menu from the Advanced tab of the config, then choosing the appropriate menu item from the Develop menu.

Conclusions

Whilst Firebug is still by far the best tool available for web developers, the widespread development of tools by browser developers means that cross-browser debugging and development is becoming ever easier. Hopefully the tools will foster competition, so that feature sets and stability improve in all the tools.

Cross-browser div focus and blur

Internet Explorer has for some time supported giving ‘focus’ to non-focussable elements such as divs. Firefox, by contrast, does not. Whilst this makes sense semantically, it’s often still very useful to use these triggers. For example, you can use onfocus to show a popup when a div is clicked, and close the popup when anything else is clicked on the page (in the onblur event).

There are many, many workarounds which provide this functionality, using such tricks as hidden input elements, global onclick handlers, and so on, but the simplest is simply this: give your div a tabIndex attribute. For example,

<div tabindex="-1" onfocus="document.getElementById('monkey').style.display='block'" onblur="document.getElementById('monkey').style.display='none'">Click to show another div.</div>
<div id="monkey" style="display:none;">Click elsewhere to hide this div.</div>

works perfectly in Firefox, Internet Explorer, and Chrome as shown in the example below:

Click to show another div.

You can also achieve a similar effect purely with CSS:

<style>
#focus-example > .extra { display: none; }
#focus-example:focus > .extra { display: block; }</style>
<div id="focus-example" tabindex="0">
  <div>Focus me!</div>
  <div class="extra">Hooray!</div>
</div>
Focus me!
Hooray!

Because the second example shows or hides a child element, the parent element will remain focussed if the user interacts with the child element, or its children. This allows you to embed links, forms, videos, and so on in the child element.

The value of tabIndex can have significance, too:

  • -1: The user can’t tab to the element, but it can be given focus programmatically (element.focus()) or by being clicked on.
  • 0: The user can tab to the element, and its order in the tabbing is automatically determined.
  • >0: Give the element a priority, with ’1′ being the highest priority.

I originally discovered this technique on this CodingForums.com thread.

Geany IDE: Tango dark colour scheme

Now on GitHub

I’ve decided to host this theme on GitHub, in the hopes that it will be easier for people to contribute, modify, and extend it. Head over to the GitHub page to download and/or fork the theme!

Recent changes

  • Added in batisteo’s python filetype — much appreciated!
  • I’ve updated the scheme slightly, to better support CSS3 functionality, JavaScript highlighting, and more languages. The list of supported languages below has been updated.

Geany is a lightweight IDE for Linux and Windows, and it’s quickly become my favourite, even going so far as to supplant VIM in many of my day-to-day tasks. I’ve started putting together a dark Tango-based theme for the Geany IDE. So far, the coloured filetypes include:

  • C
  • C++
  • CSS
  • HTML
  • Java
  • Javascript
  • PHP
  • SGML
  • Shell scripts
  • XHTML

The colours are loosely based on the Dark Geany project.

Get it from GitHub! (Or download the original package, which is probably out of date.)

Geany dark Tango colour scheme screenshot