PHP-Scraping - Submit a form for Javascript "onclick" via curl - php

Question

I would call a javascript-Function on a Remote-Server via Curl + PHP. The Submit-Button is a div-Element and call a function in by 'onclick'.
Steps of Scraper:
1. Login
2. Save session
3. Call a secure-link with session
Question: How to submit a form for Javascript "onclick" via curl?
I would implement a PHP-Scraper for following form:
<script language="JavaScript" type="text/javascript">
function logon() {
if(document.forms['form1'].elements["USERNAME"].value==""){
alert('foo');
document.forms['form1'].elements["USERNAME"].focus();
return paxReturn(false);
}
if(document.forms['form1'].elements["PASSWORD"].value==""){
alert('foo');
document.forms['form1'].elements["PASSWORD"].focus();
return paxReturn(false);
}
if (mywindow!=null) {
showObjectWithSrvlt('paxInfo','LoginServlet');
}
if((mywindow==null)||(mywindow.closed)) {
var prm ='toolbar=no,titlebar=no,directories=no,menubar=no,resizable=yes,scrollbars=yes,width=900,height=600,top=0,left=0';
mywindow = window.open("",'bar',prm);
}
document.forms['form1'].target = 'bar';
try{
mywindow.resizeTo(screen.width,screen.height);
}catch(e) {}
document.forms['form1'].submit();
try{
mywindow.focus();
}catch(e) {}
document.forms['form1'].elements["USERNAME"].value="";
document.forms['form1'].elements["PASSWORD"].value="";
/* grecaptcha.reset(); */
}
</script>
<form name="form1" method="post" target="foo" action="foo.jsp">
<input class="FormText" type="hidden" name="clickedButton" id="clickedButton" value="">
<input class="FormText" type="hidden" name="paxInfo" id="paxInfo" value="">
<div class="col-lg-10 col-md-12">
<div class="card mask">
<br>
<br>
<table class="login-table-list">
<tbody><tr>
<td><div align="right">Username: </div></td>
<td><input type="text" name="USERNAME" value="" maxlength=" 20" size=" 18" class="InputText " id="USERNAME" autocomplete="OFF"></td>
</tr>
<tr><td colspan="2"> </td></tr>
<tr>
<td><div align="right">Password: </div></td>
<td><b><input class="InputText" type="password" name="PASSWORD" size="18" value="" onkeypress="javascript:return login(event);" autocomplete="off"></b></td>
</tr>
<tr><td colspan="2"> </td></tr>
<tr>
<td></td>
<td>
<div style="width:27%; float:left;" class="stdbtnnrmWithFrameNoImage login-btn" onclick="javascript: if (disableButtonContent(this,false)) { logon() } ">
Login
</div>
</td>
</tr>
</tbody></table>
<br>
<br>
</div>
</div>
</form>
Thanks in advance for your help!