Is there any other parameter like `this` in div name.first in javascript

I see some thing like

$(#content).children(".p:first");

call the first <p> tag, except first, Is there any other parameter? thanks.

exaple:

<div id="content">
<p>aaa</p>
<p>bbb</p>
开发者_运维百科<p>ccc</p>

use $(#content).children(".p:first"); echo

<div id="content">
<p>aaa</p>
</div>

Is there any $(#content).children(".p:second"); or $(#content).children(".p:last"); can be set?

I'm still not absolutley sure what you are trying to do, but I guess you try to query for a specfic index from elements.

So let's assume you want to only grab the first <p> tag which is a children from #content, that would look like:

$('#content p:first') 

which is aquivalent with

$('#content').find('p:first');

Same example for the last <p> tag:

$('#content p:last');

If you need to query for an even more specific index, you can apply a :eq() selector or the method .eq(). Example for the second <p> tag:

$('#content').find('p').eq(1); // zero based index, 1 is the second node

References: :first, :last, :eq, .eq()

Is there any $(#content).children(".p:second"); or $(#content).children(".p:last"); can be set?

:last already exists - see the documentation here.

:second is not there, but could be implemented the easy way:

$('p:first').next() or, with a custom selector:

$.expr[':'].second= function(
    objNode,
    intStackIndex,
    arrProperties,
    arrNodeStack
    ) {

    return intStackIndex == 1;
}

This now allows you to do $('element:second'). See the jsFiddle here: http://jsfiddle.net/6xY6D/