Make it a little more difficult to view a page outside of an iframe

frame-checker-cookie.js

// Top = Self we are not in an iframe
if (top === self) {
  top.location.replace('https://url/to/redirect/to');
  
  // set a cookie called 'restricted'
  document.cookie = "restricted=true; path=/";
}

// check for 'restricted' cookie
var regexp = new RegExp("(?:^restricted|;\s*restricted)=(.*?)(?:;|$)", "g");
var result = regexp.exec(document.cookie);

if (result === null) {
  // no 'restricted' cookie
} else {
  // 'restricted' cookie found, do something
  // like hide HTML or showing a message
}

frame-checker-simple.js

// Top = Self we are not in an iframe
if (top === self) {
  top.location.replace('https://url/to/redirect/to');
}