h5配合ajax无刷新上传图片【原创】

var xmlhttp;
if (window.XMLHttpRequest)
{
   xmlhttp=new XMLHttpRequest();
}
else
{
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}

xmlhttp.upload.onprogress = function (ev) { 
                var percent = 0; 
                if(ev.lengthComputable) { 
                    percent = 100 * ev.loaded/ev.total; 
                    //document.getElementById('progress').innerHTML = percent; 
                    document.getElementById('bar').style.width = percent + '%'; 
                } 
}