：nth-of-type（）在jQuery / Sizzle？ [英] :nth-of-type() in jQuery / Sizzle?
问题描述
令我惊讶的是， Sizzle （jQuery使用的选择器引擎）附带了一个内置的：nth-child（）选择器，但缺少：nth-of-type（）选择器。
为了说明：nth-child（）和：nth-of-type（）并说明问题，请考虑以下HTML文档：
<！doctype html>
< html>
< head>
< meta charset =utf-8>
< title>：Sizzle / jQuery中的nth-of-type（）？< / title>
< style>
body p：nth-of-type（2n）{background：red; }
< / style>
< / head>
< body>
< p>以下CSS应用于此文档：< / p>
< pre> body p：nth-of-type（2n）{background：red; }< / pre>
< p>这是段落＃1。< / p>
< p>这是段落＃2。 （应匹配。）< / p>
< p>这是第＃3段。< / p>
< p>这是第4段。 （应匹配。）< / p>
< div>这不是一个段落，而是一个< code> div< / code>。< / div>
< p>这是第＃5段。< / p>
< p>这是第6段。 （应匹配。）< / p>
< script src =http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js>< / script>
< script>
$（function（）{
//下面应该给出每秒的段落（在应用CSS之后已经有红色背景的段落）橙色背景
// $（'body p：nth-of-type（2n）'）css（'background'，'orange'）;
}）;
< / script>
< / body>
< / html>因为Sizzle使用浏览器本身的 querySelector（） c>和 querySelectorAll（）方法（即在已经实现 Selectors API ），像 $（'body p：nth-child'）; 它不能在旧的浏览器中工作，因为Sizzle没有为这个选择器的后备方法。
可以轻松地添加：nth -of-type（）选择器到Sizzle，或者在jQuery中实现它（通过使用内置的：nth-child（） selector ，可能）？具有参数的自定义选择器将是很好。
解决方案
/ **
*
*返回false以排除当前元素
* /
$ .expr ['：'] ['nth-of-type'] = function（elem，i，match）{
if（match [3] .indexOf（n）=== -1）return i + 1 == match [3];
var parts = match [3] .split（+）;
return（i + 1 - （parts [1] || 0））％parseInt（parts [0]，10）=== 0;
};
测试用例 - （检入IE或重命名选择器）
： = match [3] ==even？ 2N：match [3] ==odd？ 2n + 1：match [3];
It surprised me that Sizzle (the selector engine jQuery uses) comes with a built-in :nth-child() selector, but lacks an :nth-of-type() selector.
To illustrate the difference between :nth-child() and :nth-of-type() and to illustrate the problem, consider the following HTML document:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>:nth-of-type() in Sizzle/jQuery?</title>
<style>
body p:nth-of-type(2n) { background: red; }
</style>
</head>
<body>
<p>The following CSS is applied to this document:</p>
<pre>body p:nth-of-type(2n) { background: red; }</pre>
<p>This is paragraph #1.</p>
<p>This is paragraph #2. (Should be matched.)</p>
<p>This is paragraph #3.</p>
<p>This is paragraph #4. (Should be matched.)</p>
<div>This is not a paragraph, but a <code>div</code>.</div>
<p>This is paragraph #5.</p>
<p>This is paragraph #6. (Should be matched.)</p>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js"></script>
<script>
$(function() {
// The following should give every second paragraph (those that had red backgrounds already after the CSS was applied) an orange background.
// $('body p:nth-of-type(2n)').css('background', 'orange');
});
</script>
</body>
</html>
Since Sizzle uses the browser-native querySelector() and querySelectorAll() methods if those are present (i.e. in browsers that already implement the Selectors API), stuff like $('body p:nth-child'); will of course work. It won’t work in older browsers though, because Sizzle has no fallback method for this selector.
Is it possible to easily add the :nth-of-type() selector to Sizzle, or to implement it in jQuery (by using the built-in :nth-child() selector, perhaps)? A custom selector with parameters would be nice.
/**
* Return true to include current element
* Return false to exclude current element
*/
$.expr[':']['nth-of-type'] = function(elem, i, match) {
if (match[3].indexOf("n") === -1) return i + 1 == match[3];
var parts = match[3].split("+");
return (i + 1 - (parts[1] || 0)) % parseInt(parts[0], 10) === 0;
};
Test case - (check in IE or rename the selector)
You can of course add even & odd too:
match[3] = match[3] == "even" ? "2n" : match[3] == "odd" ? "2n+1" : match[3];
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