How does js set div not to be displayed in an iframe frame

2020-03-30 00:44:28
OfStack

 
<html xmlns="http://www.w3.org/1999/xhtml" > 
<head runat="server"> 
<title> test </title> 
<script language="javascript" type="text/javascript"> 

function getStyle() { 

if (window.top == window.self) { 

document.getElementById("top").style.display = 'block'; 

} else { 

document.getElementById("top").style.display = 'none'; 


} 

} 
</script> 

</head> 
<body onload="getStyle();"> 
<form id="form1" runat="server"> 
<div id="top"> 
 Does not show in the framework, normal access display  
</div> 
</form> 
</body> 
</html>

Div top is displayed when the current page is accessed normally

The page does not display div top when the current page is in the iframe