此站点返回通过powershell返回登录页面，但在浏览器/ HttpFox中将返回一串JSON
代码：
$rep= Invoke-WebRequest -Uri $myURI -Method Post -Body "$myPOSTbody" -ContentType "application/json; charset=utf-8" -websession $SesVar -useragent $useragent
返回：
<HTML><HEAD><TITLE></TITLE></HEAD><BODY onLoad="document.AUTOSUBMIT.submit();">This page is used to hold your data while you are being authorized for your request.<BR><BR>You will be forwarded to continue the authorization process. If this does not happen automatically, please click the Continue button below.<FORM NAME="AUTOSUBMIT" METHOD="POST" ENCTYPE="application/x-www-form-urlencoded" ACTION="/public/login/wfnlogin.fcc?TYPE=aType&REALMOID=reallyLongKey"><INPUT TYPE="SUBMIT" VALUE="Continue"></FORM></BODY></HTML>
如何让它等待在$ rep变量中返回JSON？