child-autofocus.html (541B)
1 <!DOCTYPE html> 2 <input id="target" value="This should be unfocused!" autofocus></input> 3 4 <script> 5 let got_focus = false; 6 document.getElementById("target").addEventListener("focus", () => { 7 got_focus = true; 8 }); 9 10 window.addEventListener("load", () => { 11 parent.postMessage("child_loaded", "*"); 12 }); 13 14 window.addEventListener("message", event => { 15 if (event.data == "report_focus_state") { 16 let msg = got_focus ? "child_is_focused" : "child_is_not_focused"; 17 parent.postMessage(msg, "*"); 18 } 19 }); 20 </script>