.NET Answers

So far in our examination of jQuery we’ve seen how to select an ID, select a set of elements by tag name and select a set of elements by their class.  But what if we wanted to select a set of elements based on some other condition?

As the title of this post suggest, all you need is a basic knowledge of XPath statements and you are all set.

Now, you may be thinking, “Why would I even want to do this?”

Well, I have a perfect example.  Let’s say that you want to style all of your external links one way, all of the email hyperlinks another way, and all of your internal links a third way.

You could add the class keyword to each of those elements as you are coding the page.  But what if you don’t have the source code, or later want to style it in some other way?  You have to search for each of those types.

So, for example, you could select all of the hyperlinks that use the mailto: prefix by using the following line:

$('a[@href^="mailto:"]')

This selects all of the anchor tags with an href attribute starting with ‘mailto:’.

Obviously, to use this you are going to need some knowledge of XPath statements, something a lot of us have ignored for some time.  Well, just like you can’t afford to ignore JavaScript anymore, you can’t afford to ignore XPath statements.

Here are some resources that you might find helpful:

• XML Path Language Spec at the W3C
• XPath Tutorial at W3Schools
• XPath Examples at MSDN

Other places talking about jQuery and XPath:

• Use jQuery and quickSearch to interactively search any data | Encosia – If you’ve dealt with XPath for querying XML documents in the past, you’re going to love LINQ to XML. For example, these few lines of code are all that is required to execute the API request and extract a collection for databinding: …
• Designers and Developers: Back Together Again Through Microformats … – JQuery is, at its most basic, a Javascript library designed with a lot of utility functions to make programming quicker and easier. Every Javascript library says it does that. But thinking of JQuery as simply “yet another library you …
• using jquery selectors – what’s so nice about jquery is that the browser doesn’t need to support the css3 specification for you to use them within the framework itself. those familiar with xpath will also be happy to know that simple xpath selectors are also …