less mixin or selector to change position based on sibling index?

问题

I'm trying to adjust the position of several sibling divs based on which sibling they are. Currently, they're all position: absolute, but that's not set in stone.

They are each a few hundred pixels tall, but I want them to overlap each other so that the ones behind only 'peek' out above the ones in front by a few pixels. The easiest way I can think of to do this would be a Less mixin for nth-of-type that, instead of only applying the rules to the matching one index, instead passes the index into the mixin. Basically, I want this:

&:nth-of-type(@n) {
    top: @n * 20px;
}

Edit: what I'm currently doing:

&:nth-of-type(1) {
    .card_offset(1);
}
&:nth-of-type(2) {
    .card_offset(2);
}
&:nth-of-type(3) {
    .card_offset(3);
}
&:nth-of-type(4) {
    .card_offset(4);
}

Obviously this is nonoptimal. Is there a better way to do this in Less?

Alternatively, is there a CSS field for something like 'layout-height' that would give the div a certain height (not its full height) in the layout?

回答1:

Assuming you know the number of elements in advance (or are recalculating your css on the fly somehow), then essentially what you have works if put into a loop structure which I originally discovered here on stack overflow.

LESS Code

.loop(@index) when (@index > 0) {
     //set top amount
    &:nth-of-type(@{index}) { //NOTE: 1.3.3 and under is just @index, not @{index}
        top: @index * 20px;
    }

     // next iteration
     .loop(@index - 1);
}

// end the loop when index is 0
.loop(0) {}

.yourElem {
    @n: 6; //num of elements (could skip this and just put number in)
    .loop(@n);
}

Outputs

.yourElem:nth-of-type(6) {
  top: 120px;
}
.yourElem:nth-of-type(5) {
  top: 100px;
}
.yourElem:nth-of-type(4) {
  top: 80px;
}
.yourElem:nth-of-type(3) {
  top: 60px;
}
.yourElem:nth-of-type(2) {
  top: 40px;
}
.yourElem:nth-of-type(1) {
  top: 20px;
}

回答2:

I don't see a way that this is possible. Would be pretty cool, but I guess that's what javascript is for.

$('.parentDiv').children('div').each(function() {
    $(this).css({"top": num * 20 + "px"});
    num = num + 1;
});

Here's the full js solution: http://jsfiddle.net/VbuQ9/

You can play around with the LESS fiddle here if you want. http://jsfiddle.net/hV8sX/1/

来源：https://stackoverflow.com/questions/13554978/less-mixin-or-selector-to-change-position-based-on-sibling-index

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