Development Tools - Web Standards: Mastering HTML5, CSS3, and XML - page 394

Validator and Debugger Plug-ins
Browsers can also be extended with additional functionality by installing developer plug-ins, many of which are
freely available.
There are numerous add-ons for Firefox that can be useful for developers [43]. For example, HTML Validator is an
extension that adds HTML validation inside Firefox [44]. It clearly indicates the number of markup errors as an icon in
the status bar when browsing. Live HTTP Headers displays HTTP headers of a page and while browsing [45]. FireFTP
is a free, secure, cross-platform (S)FTP client for the browser [46]. The User Agent Switcher extension adds a menu
and a toolbar button to switch the user agent of the browser [47]. The IE Tab extension supports Internet Explorer
rendering from IE6 to IE9, which can be useful for testing purposes [48]. The Web Developer extension adds various
web developer tools to a browser, such as the option to disable certain styles or display CSS by media type [49]. One of
the most comprehensive developer add-ons for Firefox is Firebug [50]. It integrates several development tools to the
browser to directly edit, debug, and monitor HTML, CSS, and JavaScript (Figure 11-10 ).
Figure 11-10. Firebug in action
Some of these Firefox tools are also available under Chrome (for example, Firebug [51], Web Developer [52]), and
the ones that do not have a Chrome version have their equivalents for Chrome (such as IE Tab [53]). There are many
other developer tools under Chrome [54], such as W3C HTML5 & CSS3 Validator [55], Validity that validates the markup
from the address bar (or with hotkeys) [56], colorPicker [57], XML Tree [58], Resolution Test [59], just to mention a few.
Testing Web Pages in Text Browsers
Testing a web site in text browsers such as Lynx [60] is the best method to check information availability without styles
and graphics 4 as well as accessibility. Properly designed web content remains usable in text browsers (Figure 11-11 ),
while a large share of web sites do not.
4 Lynx cannot display nontext contents by default, but external programs can be launched from Lynx such as image viewers
or video players.