how to use nth-of-type for classes — not elements

问题:

This question already has an answer here:

• CSS3 selector :first-of-type with class name? 8 answers
• css3 nth of type restricted to class [duplicate] 2 answers

I am working on a simple HTML for an image gallery. Each row of the gallery can have 2, 3 or 4 images. (In an 2-image row, each image element is named type-2, the same goes to type-3 and type-4.)

Now I want to select the last element of each row to set a custom margin. My HTML is like this:

<div id="content">
    <div class="type-2"></div>
    <div class="type-2"></div> <!-- I want this, 2n+0 of type-2 -->
    <div class="type-3"></div>
    <div class="type-3"></div>
    <div class="type-3"></div> <!-- this, 3n+0 of type-3 -->
    <div class="type-4"></div>
    <div class="type-4"></div>
    <div class="type-4"></div>
    <div class="type-4"></div> <!-- this, 4n+0 of type-4 -->
    <div class="type-2"></div>
    <div class="type-2"></div> <!-- this -->
    <div class="type-3"></div>
    <div class="type-3"></div>
    <div class="type-3"></div> <!-- this -->
    <div class="type-4"></div>
    <div class="type-4"></div>
    <div class="type-4"></div>
    <div class="type-4"></div> <!-- this -->
</div>

I think the following CSS would work but it didn't:

.type-2:nth-of-type(2n+0) {margin-right:0;}
.type-3:nth-of-type(3n+0) {margin-right:0;}
.type-4:nth-of-type(4n+0) {margin-right:0;}

What this CSS selects is:

<div id="content">
    <div class="type-2"></div>
    <div class="type-2"></div> <!-- selected by .type-2:nth-of-type(2n+0) -->
    <div class="type-3"></div> <!-- selected by .type-3:nth-of-type(3n+0) -->
    <div class="type-3"></div>
    <div class="type-3"></div>
    <div class="type-4"></div>
    <div class="type-4"></div>
    <div class="type-4"></div> <!-- selected by .type-4:nth-of-type(4n+0) -->
    <div class="type-4"></div>
    <div class="type-2"></div> <!-- selected by .type-2:nth-of-type(2n+0) -->
    <div class="type-2"></div>
    <div class="type-3"></div> <!-- selected by .type-3:nth-of-type(3n+0) -->
    <div class="type-3"></div>
    <div class="type-3"></div>
    <div class="type-4"></div>
    <div class="type-4"></div> <!-- selected by .type-4:nth-of-type(4n+0) -->
    <div class="type-4"></div>
    <div class="type-4"></div>
</div>

I can edit my HTML to achieve what I want, but just out of curiosity, is there some kind of CSS for this?

Edit: this question may look like a duplicate of questions asking if nth-child and nth-of-type can be applied to classes -- not elements. I already knew the answer is no. What I'm really asking for is a pure CSS solution/hack for it, and the chosen answer did just that.

回答1:

With only CSS hacks, without modifying your markup, you can do something like the below:

[class*=' type-'], [type^='type-']{ /* Set all the divs to float: left initially */
    float: left;
    content: url('http://static.adzerk.net/Advertisers/db5df4870e4e4b6cbf42727fd434701a.jpg');
    height: 100px; width: 100px;
}

.type-2 + .type-2 + div{
    clear: both; /* Clear float for a div which follows two div with class type-2 */
}

.type-3 + .type-3 + .type-3 + div {
    clear: both; /* Clear float for a div which follows three div with class type-3 */
}

.type-4 + .type-4 + .type-4 + .type-4 + div {
    clear: both; /* /* Clear float for a div which follows four div with class type-4 */
}

Demo Fiddle

回答2:

This is not possible to do with CSS Selectors Level 3 (at least, without CSS hacks, extra markup, or JavaScript).

The draft CSS Selectors Level 4 proposes the :nth-match() pseudo-class, which would do what you want:

:nth-match(2n+0 of .type-2) {margin-right:0;}
:nth-match(3n+0 of .type-3) {margin-right:0;}
:nth-match(4n+0 of .type-4) {margin-right:0;}

This is not yet implemented by any browser that I know of, but there is a bug filed to implement it in Chrome.

回答3:

nth-child and nth-of-type are pseudo classes and can only be applied to elements.

.layout:nth-of-type is a pseudo-class of a class and so will not work.

Jquery's EQ might offer a solution

http://api.jquery.com/eq/

回答4:

Short answer

There is no way to do what you're asking in pure css.

Why

:nth-of-type Can only be used against an element selector like so:

div:nth-of-type(2n+0) { margin-right: 0; }

Reference link.

Possible JS solution

You can try your luck with some jQuery though:

var $this;

$('[class^="type-"]').each(function (){

  $this = $(this);

  if ( $this.attr('class') !== $this.next().attr('class') )
    $this.addClass('last');

});

Then use .type-2.last to access your "last row of type".

Demo

Heres a demo.