This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The policy read-only property of the Document interface returns the Policy interface which provides a simple API for introspecting the feature policies applied to a specific document. 
var policy = HTMLIFrameElement.policy
The Policy interface.
| Specification | Status | Comment | 
|---|---|---|
| Unknown | Unknown | Initial definition. | 
| Desktop | ||||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
| Basic support |  69
  | 
No | No | No |  56
  | 
No | 
| Mobile | |||||||
|---|---|---|---|---|---|---|---|
| Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
| Basic support |  69
  | 
 69
  | 
No | No |  56
  | 
No | ? | 
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
    https://developer.mozilla.org/en-US/docs/Web/API/document/policy