效果预览：

程序代码：

<iframe id="editor" width="90%" height="100"></iframe> <script>editor.document.designMode="on";</script><input type="button" value="获取图片" onclick="getImg();" />
  <script type="text/javascript">
  <!--
        function getImg()
    {
        var str_img = editor.document.body.innerHTML.replace(/[\s\S]*?src=[\'\"\s]*?(http:\/\/[a-z\d\._\-\/\%]*)[\'\"\s]*?/igm, '$1,');
        var imgs = str_img.split(',');
        str_img = '';
        for (var i=0;i<imgs.length-1;i++)
        {
            if (imgs[i].indexOf('http://')==0)
            {
                if (i>0)str_img += ',';
                str_img += imgs[i];
            }
        }
        editor.document.body.innerHTML=(str_img);
    }
  //-->
  </script>