:nth-child(n)前面的空格有什么作用? [英] What does a space preceding :nth-child(n) do?
问题描述
当我编写一些CSS时,出现了在使用:nth-child(n)
之前从未遇到过的情况,并且我怀疑实际发生的情况.
While I was writing a bit of CSS, a situation that I have never encountered before using the :nth-child(n)
appeared and I was doubt of what is actually happening.
当我使用伪类时,我会在选择器之间没有空格的情况下编写它们,就像这样:
When I use pseudo classes, I write them without a space between the selector, like so:
div#wrap:hover {
border-bottom: 2px solid orange;
}
/* OR */
div#wrap:nth-child(4) {
border-bottom: 2px solid orange;
}
但是它没有按我预期的方式工作,所以我尝试在选择器和伪类之间插入一个空格.令人惊讶的是,它有效:
But it didn't work the way I expected, so I tried inserting a space between the selector and the pseudo class. Surprisingly, it worked:
div#wrap :nth-child(4) {
border-bottom: 2px solid orange;
}
这是怎么回事?
div#wrap :nth-child(4) {
border-bottom: 2px solid orange;
}
<div id="wrap">
<h1>Heading 1</h1>
<p>This is a test!</p>
<h2>Creating content</h2>
<p>The next paragraph uses the <strong>.html</strong> method to create a new element.</p>
</div>
推荐答案
您误解了选择器.它选择也是:nth-child(n)
的元素,其中也具有先前的元素作为父元素.
You're misunderstanding the selector. It selects the element that is also the :nth-child(n)
which also has the preceding element as a parent.
如果前面没有选择器,则默认为*:nth-child(n)
When there is no selector preceding, it defaults to *:nth-child(n)
因为您可能只想将其应用于直接后代,而不是将每个元素应用到其父代的第四个子代和父代的后代,所以我将使用.element > *:nth-child(n)
仅应用于直接后代.
Because you probably only want to apply this to direct descendants and not every element which is the fourth child of its parent and a descendant of the parent, I would use .element > *:nth-child(n)
to only apply to direct descendants.
div#wrap > *:nth-child(4) {
border-bottom: 2px solid orange;
}
div#wrap > *:nth-child(4) {
border-bottom: 2px solid orange;
}
<div id="wrap">
<h1>Heading 1</h1>
<p>This is a test!</p>
<h2>Creating content</h2>
<p>The next paragraph uses the <strong>.html</strong> method to create a new element.</p>
</div>
如果您想更加具体,并且仅选择第四个子元素(如果它是<p>
元素),则可以使用.element > p:nth-child(n)
.这将选择所有<p>
元素,它们是与div#wrap
选择器匹配的元素的第四个直接后代.
If you wanted to be more specific and only select the fourth child if it is a <p>
element, you can use .element > p:nth-child(n)
. This will select all <p>
elements that are the fourth direct descendant of elements matching the div#wrap
selector.
div#wrap > p:nth-child(4) {
border-bottom: 2px solid orange;
}
div#wrap > p:nth-child(4) {
border-bottom: 2px solid orange;
}
<div id="wrap">
<h1>Heading 1</h1>
<p>This is a test!</p>
<h2>Creating content</h2>
<p>The next paragraph uses the <strong>.html</strong> method to create a new element.</p>
</div>
如果要选择直接从每个div#wrap
降序的第二个<p>
元素,则可以这样使用.element > p:nth-of-type(n)
:
If you want to select the second <p>
element directly descending from each div#wrap
, you can use .element > p:nth-of-type(n)
like so:
div#wrap > p:nth-of-type(2) {
border-bottom: 2px solid orange;
}
div#wrap > p:nth-of-type(2) {
border-bottom: 2px solid orange;
}
<div id="wrap">
<h1>Heading 1</h1>
<p>This is a test!</p>
<h2>Creating content</h2>
<p>The next paragraph uses the <strong>.html</strong> method to create a new element.</p>
</div>
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