【JavaScript&jQuery】$.ajax，

$(function(){  
    $('#send').click(function(){  
         $.ajax({  
             type: "GET",  
             url: "test.json",  
             data: {username:$("#username").val(), content:$("#content").val()},  
             dataType: "json",  
             success: function(data){  
                         $('#resText').empty();   //清空resText里面的所有内容  
                         var html = '';   
                         $.each(data, function(commentIndex, comment){  
                               html += '<div class="comment"><h6>' + comment['username']  
                                         + ':</h6><p class="para"' + comment['content']  
                                         + '</p></div>';  
                         });  
                         $('#resText').html(html);  
                      }  
         });  
    });  
});