ajax上传图片

<script>
    $(‘.sub_btn‘).click(function(){
          $(this).next().trigger(‘click‘);
    })
    $(document).on(‘change‘,‘#file‘,function(){
        var form = new FormData();
        var fileObj = $(this);
        form.append(‘chat_image‘,fileObj[0].files[0]);
        $.ajax({
            type          :   ‘post‘,
            url           :   "{:U(‘index/image‘)}",
            data          :   form,
            dataType      :   ‘json‘,
            cache         :   false,
            contentType   :   false,
            processData   :   false, 
            success:function(msg)
            {
              heh = msg.replace(/"/g, "");
              img = ‘<img src="__ROOT__‘+heh+‘" width="50">‘;
              $(‘#message‘).append(img);
            }
        });
    });
  </script>