javascript 获取表单file全路径

<title>get file input full path</title>&lt;script language="javascript"&gt;
function getFullPath(obj)
{
if(obj)
{
//ie
if (window.navigator.userAgent.indexOf("MSIE")&gt;=1)
{
obj.select();
return document.selection.createRange().text;
}
//firefox
else if(window.navigator.userAgent.indexOf("Firefox")&gt;=1)
{
if(obj.files)
{
return obj.files.item(0).getAsDataURL();
}
return obj.value;
}
return obj.value;
}
}
&lt;/script&gt;<input type="file"><img id="img">