<!-- BUGS: Please use this template. --> <!-- QUESTIONS: This is not a general support forum! Ask Qs at http://stackoverflow.com/questions/tagged/typescript --> <!-- SUGGESTIONS: See https://github.com/Microsoft/TypeScript-wiki/blob/master/Writing-Good-Design-Proposals.md --> **TypeScript Version:** 2.0.3 **Code** ``` ts let xhr = new XMLHttpRequest(); console.log(xhr.responseURL); ``` **Expected behavior:** The compiler should be able to compile the code without errors. Here is the [MDN documentation for this property](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/responseURL). **Actual behavior:** `tsc` complains: ``` error TS2339: Property 'responseURL' does not exist on type 'XMLHttpRequest'. ```