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Detailed explanation of CSS3 complex selectors

高洛峰Original: 2017-03-24 11:22:241566browse

Today I finished watching the CSS3 complex selector part in the video, and let’s sort out the knowledge points I learned.

1. Sibling selector: at the same position level, it can be called a sibling element

a, Adjacent sibling selector:next
Following [the one immediately after the current element] (one), specifying the selector element
Syntax: Use "+" as the conjunctive symbol
eg: p+p ->p immediately following p Element

<!-- demo.html -->
<html>
    <head>
        <title></title>
    </head>
    <body>
        <p>这是第一个段落</p>
　　  <div id="d1">这是一个div</div>
　　  <span>这是一个span</span>
        <p class="p1">这是第二个段落</p>
　　  <b>Hello World</b>
　　  <p class="p2">这是第三个段落</p>
    </body>
</html>

/*demo.css*/
div+p{
    background: yellow;
}
#d1+p{
    background: red;
}
span+.p1{
    background: blue;
}

b, Universal sibling selector: next_all
Matches [all subsequent] sibling elements of a certain element that satisfy the specified selector
Syntax: Use "~" as the conjugator
eg: p~p{} -> Match all p

2, Attribute selector: Use the element attached Attributes, used in selectors as conditions for selecting elements
Syntax: [attribute-related content]
eg: [id] ->All elements with id attributes
p[id] -> ;p element with id attribute
a.[id],p[id]
b.p[id][class] ->p element with both id and class
c, p[id="p1"] ->p element with id value "p1"
d, p[class~="value"]
e, p[class^=" b"] -> Match the p tag whose class attribute value starts with b
f, p[class*="b"] -> Match the p tag whose class attribute value contains b
g, p[ class$="b"] -> Match the p tag whose class attribute value ends with b

<!-- demo.html -->　　　　　
 <html>
     <head>
         <title></title>
     </head>
     <body>
        <p class="clear p1 myself">
        这是第四个段落
        </p>
        <div class="userContent">
        文本内容
        </div>
     </body>
</html>

/*demo.css*/
p[class]{
color: #e4393c;
}
p[class~=&#39;p1&#39;]{
background-color: #cd2c2d;
color: #fff;
}
div[class ^= "us"]{
background-color: #bfb;
}
div[class$="t"]{
background-color: #bfb;
color: #333;
}

3. PseudoClass selector
a.Targetpseudo class : Highlight active HTMLAnchor point
Syntax::target
b. Element StatePseudo class: Mostly used on form elements
1 , :enabled -> Matches every enabled element
2. :disabled -> Matches every disabled element
3. :checked -> Matches selected form elements (only Applicable to checkbox, radio)
c. Structural pseudo-class
1. :first-child -> Matches the first child element that belongs to its parent element
2.: last-child -> Matches the last child element belonging to its parent element
3. :empty -> Matches elements that have no child elements (text content or spaces are also counted as child elements)
4.: only-child -> Matches the only child element that belongs to its parent element
d. Negative pseudo-class: matches elements with non-specified selectors
Syntax::not(selector)

<!-- demo01.html 目标伪类 -->
 <html>
     <head>
         <title></title>
     </head>
     <body>
    <a href="#Tom">猫和老鼠(Tom and Jerry)</a>
    <a href="#Atongmu">铁臂阿童木</a>
    <a href="#BlackCat">黑猫警长</a>
    <br>
    <a name="Tom">第一部：Tom and Jerry</a>
    <p style="height: 500px;">Tom and Jerry</p>
    <div id="Atongmu" style="height: 500px;">我是阿童木</div>
    <div id="BlackCat" style="height: 500px;">I am Mr Black Cat</div>    
     </body>
</html>

/*demo01.css*/
a:target,div:target{
    background-color: #bfb;
    font-size: 20pt;
}

<!-- demo02.html 结构伪类 -->　　　　　
 <html>
     <head>
         <title></title>
     </head>
     <body>
    <div id="d1"></div>
    <div id="d2">
        <p>This is a p</p>
    </div>
    <div id="d3">
        This id d3
    </div>
    <div id="d4">
        <b>first</b>
        <b>second</b>
        <b>third</b>
        <b>last</b>
    </div>    
     </body>
</html>

/*demo02.css*/
div{
    width: 100px;
    height: 100px;
}
b{
    display: block;
}
div:empty{
    background-color: #bfb;
}
p:only-child{
    background-color: #fbf;
}
b:first-child{
    font-size: 2em;
    color: #fbb;
}
b:last-child{
    font-size: 3em;
    font-weight: normal;
    color: #bbf;
}

<!-- demo03.html 伪元素状态伪类 -->
  <html>
      <head>
          <title></title>
      </head>
      <body>
         用户名称：<input type="text"><br>
    用户昵称：<input type="text" disabled value="请输入您的昵称">
    <br>
    性别：<input type="radio" name="rdoGender">男
              <input type="radio" name="rdoGender">女 
      </body>
 </html>
 
 /*demo03.css*/
 input:enabled{
    color: red;
}
input:disabled{
    border: 1px solid #f00;
}
input[name=rdoGender]:checked{
    background-color: #bfb;
}

<!-- demo04.html 否定伪类 -->
  <html>
      <head>
          <title></title>
      </head>
      <body>
         <div>
        用户名称：<input type="text"><br>
        用户密码：<input type="password"><br>
        <input type="submit" value="提交">
        <input type="button" value="按钮">
    </div>
      </body>
 </html>
 
 /*demo04.css*/
input:not(:last-child){
    border: 1px solid #f00;
}

4 , Pseudoelement selector: All matched are text contents
a.:first-letter ->Match the first character
b.:first -line -> Match the first line
The above two selectors, inline elements are invalid, inline blocks and block levels can
c.::selection ->Used for the text style selected by European compensation users (Firefox seems to be incompatible)

<!-- demo.html 为元素选择器 -->
  <html>
      <head>
          <title></title>
      </head>
      <body>
         <p>
        风风雨雨适合于独行，且手中无伞，不打伞有不打伞的好处。湿是我的湿，冷是我的冷，即便化作雨点般的小，那么小也是我的小。
    </p>
    <span>
        风风雨雨适合于独行，且手中无伞，不打伞有不打伞的好处。湿是我的湿，冷是我的冷，即便化作雨点般的小，那么小也是我的小。
    </span>
      </body>
 </html>
 
 /*demo.css*/
p{
    width: 200px;
    border: 1px solid #bfb;
    margin: 10% auto;
    text-indent: 5px;
}
span{
    /*float: right;*/
    /*display: inline-block;*/
    position: absolute;
    top: 300px;
    left: 500px;
    
}
p:first-letter{
    font-size: 20pt;
    color: #fbb;
}
p:first-line{
    font-style: italic;
}
span:first-line{
    font-style: italic;
    background-color: #ffb;
}
p::selection{
    background-color: #bbf;
    color: #fbf;
}

The above is everything I learned in the video. If there are any errors or deficiencies, I hope viewers will point them out and correct them in time. .

Today is the second day since I opened my blog. This is the first article I have written. I publish it here purely as my own study notes, hoping to record my growth.

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