Prototype – 元素对象 previous() 方法

如果指定的索引与cssRule 匹配，则此方法返回元素的前一个兄弟元素或索引的第一个元素。如果未提供 cssRule，则考虑所有先前的兄弟姐妹。如果没有以前的兄弟符合这些条件，则返回 undefined。

语法

element.previous([cssRule][, index = 0] );

返回值

返回 HTML 元素。如果没有以前的兄弟符合这些条件，则返回 undefined。

例子

<html>
   <head>
      <title>Prototype examples</title>
      <script type = "text/javascript" src = "/javascript/prototype.js"></script>
      
      <script>
         function showResult() {
            var str = $('saying').previous();
            alert( "$('saying').previous() " + str.innerHTML );

            var str = $('saying').previous(0);
            alert( "$('saying').previous(0) " + str.innerHTML  );
   
            var str = $('saying').previous('h3');
            alert( "$('$('saying').previous('h3') " + str.innerHTML  );

            var str = $('ida-red').previous( '.yummy');
            alert( "$('ida-red').previous( .yummy ) " + str.innerHTML );

            var str = $('ida-red').previous( 5 );
            alert( "$('ida-red').previous() " + str );
         }
      </script>
   </head>

   <body>
      <p>Click the button to see the result.</p>
      
      <ul id = "fruits">
         <li id = "apples">
            <h3 id = "title">Apples</h3>
            <ul id = "list-of-apples">
               <li id = "golden-delicious">Golden Delicious</li>
               <li id = "mutsu">Mutsu</li>
               <li id = "mcintosh" class = "yummy">McIntosh</li>
               <li id = "ida-red" class = "yummy">Ida Red</li>
            </ul>
            <p id = "saying">An apple a day keeps the doctor away.</p>  
         </li>
      </ul>
      <br />
      
      <input type = "button" value = "Show Result" onclick = "showResult();"/>
   </body>
</html>

返回到：Prototype – 元素对象

作者：terry，如若转载，请注明出处：https://www.web176.com/prototype_api/9055.html