There is a long history with this site. see previously https://github.com/WebKit/WebKit/commit/0b543cc9ff31a50857a570a65f9d33f405b30a15 and https://github.com/WebKit/WebKit/pull/17329/files The hypothesis this is still broken is because it doesn't try to match `.ceac.state.gov`, just `ceac.state.gov` To note that the real issue is about Bug 267449 which manifests itself on this site by There is a beforeunload if (window.addEventListener) { window.addEventListener("beforeunload", ClearSession, false); } else if (window.attachEvent) { window.attachEvent("onbeforeunload", ClearSession) } It fires a ClearSession. Which triggers else if (document.location.pathname.indexOf("Default.aspx") < 0 && typeof document.activeElement != "undefined" && document.activeElement.toString().indexOf("HTMLBodyElement") > 0 || document.activeElement.toString().indexOf("HTMLInputElement") > 0) { validNavigation = false; } And triggers: this.ExitClearSession() Which triggers the e.preventDefault() if (validNavigation == false && e != undefined) { if (ieMode == "True") { e.returnValue = undefined; } else { e.preventDefault(); } And when the return is happening at the end of ClearSession it opens the alert. Firefox in the clear session is } else if ((typeof document.activeElement != "undefined" && document.activeElement != "object" && typeof document.activeElement.name != "undefined") && ( document.activeElement.toString().indexOf("aspx") > 0 || //for the left menu exclusion document.activeElement.name.indexOf("btn") > 0 || //check for button click document.activeElement.name.indexOf("Button") > 0 || document.activeElement.type == "button") || document.activeElement.id.indexOf("cbx") > 0 || document.activeElement.id.indexOf("Radio") > 0 || document.activeElement.id.indexOf("radio") > 0 || document.activeElement.id.indexOf("chkbx") > 0 || document.activeElement.id.indexOf("Button") > 0 || document.activeElement.id.indexOf("button") > 0) { // for button validNavigation = true; Firefox: document.activeElement is input Safari: document.activeElement is body This will decide if validNavigation is true or false And then will make WebKit fail for the next step. Let’s make a test https://codepen.io/webcompat/pen/zYbKgGd <input type="checkbox" id="check" onclick="logme(this)"> <div id="log"></div> With var check = document.querySelector("#check"); var log = document.querySelector("#log"); function logme(element) { log.textContent += document.activeElement; } log.textContent = check; * Firefox: HTMLInputElement * Chrome: HTMLInputElement * Safari: HTMLBodyElement but there other ways to fail too.