Question

4

Foolproof way to detect if iframe is cross domain

rated 0 times [ 11] [ 7] / answers: 1 / hits: 21677 / 12 Years ago, wed, september 12, 2012, 12:00:00

I'm trying to determine if any iframe is cross-domain or not. According to the accepted answer in this question: Detect when iframe is cross-domain, then bust out of it it says to put the code accessing the contentDocument of the iframe in a try / catch block. I tried this for a cross-domain iframe in Chrome:

try { 

  document.getElementsByTagName('iframe')[0].contentDocument;

} catch(err){

  console.log(called);

}

and it still throws the cross-domain error and does not catch the error.

I also tried to check if the protocol + host + port of the parent page url is in the src of the iframe:

function thirdPartyIframe(iframe){

  var url = document.location.protocol + // + document.location.hostname + (document.location.port ===  ?  : : + document.location.port);

  var regexp = new RegExp(url.replace(///g, \/).replace(/./g, \.));

  if (iframe.src === '' || regexp.test(iframe.src)){

    return false;

  } else {

    return true;

  }

}

but this does not seem to work for the first iframe on the homepage of Facebook with src equal to (it's long):

http://www.facebook.com/ai.php?aed=AQLlH2cfdnsnLrDUVyqrQPlWpayw9N09Z_iNuhulevbeEfVa4mcVRcT8cjAZOjQb8y1QXab5Ae3aSEJx49U_Qv35rtSp1VC9cY0_CrpOjMDk40hS_Xm57A996YtRVCcWSuRZ_jZERQ_iA_E4621NAbKHT9dsB7uElkRtTvl5K-zPI0jeH-BEnlZIOXbeEdbRC6qCwoToaltolpe-Ot2KWgkfb_vBZYpzUc3jQoEHzLG6tauO9l_hkXpYpHxnt-KYFKIFZ1PgmrHgb0UcGjeKHl7yBR1AbW2n5XgdgaAhFvBjs5GZlKy566nvl8eLRA60orwkwtWYeN8-gKoAmOLm7-6minsWn8lk1h2Qn3p07HCTSnYHfv1aJ6mF5jmuzP0YYe7Ym9ZbmK-tvax4uPAQJ2OdULilKbEh8M-2V9pVY3AC228OPlrRullZuuOg8DI2A8WeMF-fbbOdOFFVCe5Gj1CaZu3LYXiqdG7mUgY6AEpk9ZzGT4fC2K8DInQo1AypCvzG64C_bEWfODeXe0aGbkWwsUUmO7E5HFg0tvZkK5IAR_xxxQ2rlf5jbcEDo_2gdIDdHe1HT75-SJLUsSA0M8EU01oNNPuWwEC2BW6inepc9QPuqeg42tcEbKLU-rIUnXDBLvgutft8azWPPQ6_LafGjCAmC9uTalagoWLLDMpQOThvPg7YeVd7qg_c9Mzn2GAfuswcxDSxyRIZo9MaOhA6mhfXeE1tmjyBBsMxnx08tO21Jsfgch59fmMxpeJzdsNMPK3FAojfglvCQ2Zrt_6ataexUB4xlM7_PhKrfBPtxb5fe2TE9-nlWruNEpoCrzI05yv4Go3CYEWHob06K_9iICfNVTFkSYGTiJnMXCy_fdgfyzUIn5QJIPRo4-Wnyg444zKAO_nyFW59LqbIanHVfFY6ybiA6KeC3meREWzTPSsrU5d_NbYHlJWb8uPNDR04jaH5e2qiYj3Y8qgLQA5m

My function classifies it as not a third party iframe, but Chrome still throws the cross-domain error when I access its contentDocument.

I'm looking for a foolproof, cross-browser way to do this.

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kennedim

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1 Year ago

answered 12 Years ago agustindejonm · Accepted Answer

You need to do a little more than what's in your try/catch to handle different browsers and to handle different ways that browsers deal with cross domain access:

function canAccessIFrame(iframe) {

    var html = null;

    try { 

      // deal with older browsers

      var doc = iframe.contentDocument || iframe.contentWindow.document;

      html = doc.body.innerHTML;

    } catch(err){

      // do nothing

    }



    return(html !== null);

}

In your example, this would be:

var accessAllowed = canAccessIFrame(document.getElementsByTagName('iframe')[0]);

Working demo: http://jsfiddle.net/jfriend00/XsPL6/

Tested in Chrome 21, Safari 5.1, Firefox 14, IE7, IE8, IE9.