表单type:image提交Js阻止问题?有测试页
<%@   page   language= "java "   import= "java.util.* "   pageEncoding= "UTF-8 "%>  
  <% 
 	String   path   =   request.getContextPath(); 
 	String   basePath   =   request.getScheme()   +    ":// " 
 			+   request.getServerName()   +    ": "   +   request.getServerPort() 
 			+   path   +    "/ "; 
 %>    
  <!DOCTYPE   HTML   PUBLIC    "-//W3C//DTD   HTML   4.01   Transitional//EN ">  
  <html>  
 	 <head>  
 		 <base   href= " <%=basePath%>  ">    
 		 <title> My   JSP    'imageSub.jsp '   starting   page </title>    
 		 <meta   http-equiv= "pragma "   content= "no-cache ">  
 		 <meta   http-equiv= "cache-control "   content= "no-cache ">  
 		 <meta   http-equiv= "expires "   content= "0 ">  
 		 <meta   http-equiv= "keywords "   content= "keyword1,keyword2,keyword3 ">  
 		 <meta   http-equiv= "description "   content= "This   is   my   page ">  
 		 <!-- 
 	 <link   rel= "stylesheet "   type= "text/css "   href= "styles.css ">  
 	-->  
  <script>  
 function   checkInput(s) 
 { 
 	var   reg=new   RegExp( "^[\da-zA-Z0-9\u4e00-\u9fa5]*$ ", "g "); 
 	var   rs=s.search(reg); 
 	if(rs==-1) 
 	return   false; 
 	else 
 	return   true; 
 } 
 function   formsub() 
 { 
 	var   v=document.getElementById( 'sear ').value;  	 
 	var   flag=checkInput(v); 
 	if(flag) 
 	{ 
 		document.getElementById( 'f ').submit(); 
 		return   true; 
 	} 
 	else 
 	{ 
 		return   false; 
 	} 
 } 
  </script>  
 	 </head>    
 	 <body>  
 		 <form   id= "f "   action= "App/imageSub.jsp "   method= "POST ">  
 			 <dl>  
 				 <dt>  
 					 <input   class= "input "   type= "text "   id= 'sear '   name= 'sear '   value= "文本 "   />  
 				 </dt>  
 				 <dt>  
 				 <!--       <input   type= "button "   src= "http://www.csdn.net/ui/scripts/Csdn/_resources/FrameMDI/forum.gif "   onclick= "formsub() "   />    -->  
 					 <input   type= "image "   src= "http://www.csdn.net/ui/scripts/Csdn/_resources/FrameMDI/forum.gif "   onclick= "formsub() "   />  
 					 <!--   改变这两个input   一个是type:button      一个是type:image      当是前者时,表单提交前需要返回值为true,当是后者时,不论返回值是true/false   表单都提交,现在要求用type:image时,可以通过Js事件按条件阻止提交      PS:可以观察状态栏进度条判断是否提交   -->  
 				 </dt>  
 			 </dl>  
 		 </form>  
 	 </body>  
  </html>  
 ======================================================= 
 type:button 
 type:image 
 提交时Javascript能否阻止submit()的问题
------解决方案--------------------onclick= "return formsub() "