:nth-last-of-type() selector Jquery官方教程

nth-last-of-type selector

Description: Selects all the elements that are the nth-child of their parent in relation to siblings with the same element name, counting from the last element to the first.

version added: 1.9jQuery( ":nth-last-of-type(index/even/odd/equation)" )

index: The index of each child to match, starting with the last one (1), the string even or odd, or an equation ( eg. :nth-last-of-type(even), :nth-last-of-type(4n) )

Because jQuery's implementation of :nth- selectors is strictly derived from the CSS specification, the value of n is "1-indexed", meaning that the counting starts at 1. For other selector expressions such as :eq() or :even jQuery follows JavaScript's "0-indexed" counting. Given a single <ul> containing three <li>s, $('li:nth-last-of-type(1)') selects the third, last, <li>.

Further discussion of this usage can be found in the W3C CSS specification.

Examples:

Find the second to last li in each matched ul and note it.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>nth-last-of-type demo</title>
  <style>
  div {
    float: left;
  }
  span {
    color: blue;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js" rel="external nofollow"  rel="external nofollow" ></script>
</head>
<body>
 
<div>
  <ul>
    <li>John</li>
    <li>Karl</li>
    <li>Adam</li>
  </ul>
</div>
<div>
  <ul>
    <li>Dan</li>
  </ul>
</div>
<div>
  <ul>
    <li>Dave</li>
    <li>Rick</li>
    <li>Timmy</li>
    <li>Gibson</li>
  </ul>
</div>
 
<script>
$( "ul li:nth-last-of-type(2)" ).append( "<span> - 2nd to last!</span>" );
</script>
 
</body>
</html>

Demo:

This is a playground to see how the selector works with different strings.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>nth-last-of-type demo</title>
  <style>
  button {
    display: block;
    font-size: 12px;
    width: 100px;
  }
  div {
    float: left;
    margin: 10px;
    font-size: 10px;
    border: 1px solid black;
  }
  span {
    color: blue;
    font-size: 18px;
  }
  #inner {
    color: red;
  }
  td {
    width: 50px;
    text-align: center;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js" rel="external nofollow"  rel="external nofollow" ></script>
</head>
<body>
 
<div>
  <button>:nth-last-of-type(even)</button>
  <button>:nth-last-of-type(odd)</button>
  <button>:nth-last-of-type(3n)</button>
  <button>:nth-last-of-type(2)</button>
</div>
<div>
  <button>:nth-last-of-type(3n+1)</button>
  <button>:nth-last-of-type(3n+2)</button>
</div>
 
<div>
  <table>
    <tr><td>John</td></tr>
    <tr><td>Karl</td></tr>
    <tr><td>Brandon</td></tr>
    <tr><td>Benjamin</td></tr>
  </table>
</div>
<div>
  <table>
    <tr><td>Sam</td></tr>
  </table>
</div>
<div>
  <table>
    <tr><td>Glen</td></tr>
    <tr><td>Tane</td></tr>
    <tr><td>Ralph</td></tr>
    <tr><td>David</td></tr>
    <tr><td>Mike</td></tr>
    <tr><td>Dan</td></tr>
  </table>
</div>
 
<span>tr<span id="inner"></span></span>
 
<script>
$( "button" ).click(function() {
  var str = $( this ).text();
  $( "tr" ).css( "background", "white" );
  $( "tr" + str ).css( "background", "#ff0000" );
  $( "#inner" ).text( str );
});
</script>
 
</body>
</html>

:nth-last-of-type() selector