段落选择器内的标题不起作用

Question

我想将<p>标签的所有子项的背景颜色更改为绿色。但是我编写的代码不起作用。但是，如果我将<p>标签更改为<div>，则可以正常工作。但是我需要它使用jQuery Advanced Selectors在<p>标签上工作

代码：

$(document).ready(() => {
  //Change background color of children to green
  //Below code is not working
  $("#intro").children().each(function() {
    $(this).css("background-color", "green");
  });
  //Show only first 2 list item
  $('ol li').hide().slice(0, 2).show();
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.0/jquery.min.js"></script>
<p id="intro">jQuery is a lightweight, "write less, do more" JavaScript library.
  <h6>The purpose of jQuery is to make it much easier to use JavaScript on your website</h6>
</p>
<ol>
  <li>HTML/DOM manipulation</li>
  <li>CSS manipulation</li>
  <li>Effects and animations</li>
  <li>AJAX</li>
</ol>

Answer 1

[h不是p的有效子代

Paragraph P

段落是块级元素，如果在关闭</p>标记之前解析了另一个块级元素，则显然会自动关闭。

允许的内容：Phrasing content

渲染的HTML变为

<p id="intro">jQuery is a lightweight, "write less, do more" JavaScript library.
</p><!-- inserted by browser -->
<h6>The purpose of jQuery is to make it much easier to use JavaScript on your website</h6>
<p><!-- inserted by browser -->
</p>

您可以这样做：

$(document).ready(() => {
  //Change background color of children to green
  //Below code is now working
  $("#intro").children().each(function() {
    $(this).css("background-color", "green");
    $('<br />').insertBefore(this); // because of the inline-block
  });
  //Show only first 2 list item
  $('ol li').hide().slice(0, 2).show();
})

.h6 { 
    display: inline-block;
    font-size: .67em;
    margin-top: 2.33em;
    margin-bottom: 2.33em;
    margin-left: 0;
    margin-right: 0;
    font-weight: bold;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.0/jquery.min.js"></script>
<p id="intro">jQuery is a lightweight, "write less, do more" JavaScript library.
  <span class="h6">The purpose of jQuery is to make it much easier to use JavaScript on your website</span>
</p>
<ol>
  <li>HTML/DOM manipulation</li>
  <li>CSS manipulation</li>
  <li>Effects and animations</li>
  <li>AJAX</li>
</ol>