How to use evaluateJavaScript to get iframe's elements (cors)?

Hi,

While the react-native-wkwebview loads the iframe content elements correctly, I cannot get the iframe elements by issuing evaluateJavaScript js code:

var ifrm = document.getElementById("iframeID");
var ifrmContent = (ifrm.contentWindow || ifrm.contentDocument);

ifrmContent.document throws js error.

How to work around this (cors)?

Thanks!