Best Practices - Web Standards: Mastering HTML5, CSS3, and XML - page 429

The same fragment gives error messages in validators if it is written directly in the markup. The iframe version
of the button has problems too because it cannot be used in XHTML. It can be rewritten as an object (with the same
parameters), but then it stops working. Users of APIs and third-party software components often apply the previous
trick if they want their web page to validate.

■ providing markup code with document.write in Javascript is a hack that you should not use. the same
trick is applied for validating virtually any kind of otherwise incorrect markup that definitely cannot be accepted by real
web standardistas. the document will validate only because the content written in the external .js file is ignored by the
validator. this code is still not valid! how to provide such content without sacrificing either functionality or validity is an
open question in many cases, though.

Caution

Embedding YouTube Videos as Valid XHTML or HTML5
YouTube, the popular video sharing portal offers two types of embedding codes for videos:

object element with parameters and an embed
element. It supports Flash playback only.

• The older-style embed code applies the

iframe and supports both Flash and HTML5 video content. • The new embed code uses an

Under each video on YouTube, there is a Share button that provides a link to the current video with options
such as long link, HD link, and declaring a starting position for playback. After clicking on the Embed link, a text box
appears with the selected new-type embedding code ready for copying to the clipboard. Below that text box there are
further options for customizing the embedding code, such as declaring the size 4 or using the old-style embed code.
From the standardization point of view, both versions need some improvement.
In XHTML, the following issues should be addressed:

embed element contained by the older-style embedding code is invalid in XHTML. • The

iframe element used by the new-style embedding code cannot be used in XHTML 1.0
Strict or XHTML 1.1 (only in XHTML 1.0 Transitional, which should not be used). Moreover,
the data and type attributes should be provided to maximize interoperability (without them,
the embedding will not work under certain browsers). However, providing the data attribute
while preserving the movie parameter from the suggested embedding code ensures browser-
independence, because some rendering engines will use the outer declaration (the value of
the data attribute on the object element), and others will use the inner declaration (the value
of the movie parameter) to identify the resource URL (similarly to the Flash Satay method used
for Flash embedding covered in Chapter 9).

• The

In HTML5, the following issues should be addressed:

frameborder and allowscreen attributes • If you prefer the new-style embedding code, the

should not be used on the iframe element.

data and type attributes are missing from the object
element. Moreover, the param elements as well as the embed element should be closed using
the shorthand notation rather than the closing tags </param> and </embed> .

• If you want to use the old-style code, the

4 The size can also be modified arbitrarily later in the markup when using the embedding code.