Foolproof way to detect if this page is INSIDE a cross-domain iframe

Question

An answer to "Foolproof way to detect if iframe is cross domain" describes a method to test if an iframe on a page points to a same-domain or cross-domain page, working around different browsers' interpretations of the cross-domain policy and avoiding error messages that would interrupt a user or stop javascript.

I'm looking to do the equivalent of this but from the child page inside the iframe testing whether it is inside a cross-domain iframe or not.

It's possible to access (same domain) info about the parent with the parent global e.g. parent.document.location, but is there a reliable way to do this cross-browser without crashing into errors when it detects that the parent is cross-domain?

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For handy testing, here's a jsbin inside a jsfiddle that crashes into an error when trying to test if parent.location.host is accessible. Is there a reliable way to get something usable like false telling us that this is a cross-domain parent, instead of an error?

Is there a try...catch variant which will be robust cross-browser? Or maybe some clever trick using a return value from parent.postMessage()? (although the parent page cannot be edited)

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Use case: imagine embedable content that is to be embedded on pages on its own site, and by third parties. If the page is on a same-domain iframe, we hide branding and links back to the original site because the user is already here. If they access the page from a 3rd party iframe or load the page directly, we show the branding and credits so they can see the source of the content.

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To clarify, I know about the same-domain policy and I don't care what the cross browser domain is, I'm just looking to write a simple but reliable if condition like if( crossDomainParent() ){ /* do something */}

Answer 1

First check if you are IFramed.

window.self !== window.top 

If you are IFramed, then your referrer is your parent frame url.

document.referrer 

From this url you should be able to detect if you want to branch your code.

Answer 2

Real cross-browser solution for posterity:

function isCrossOriginFrame() {   try {     return (!window.top.location.hostname);   } catch (e) {     return true;   } }  console.log(isCrossOriginFrame()); 

Tested on a decent swath of desktop and mobile browsers.

https://jsfiddle.net/arzd4btc/3/