made request asynchronous

removes that ugly warning in the console about the detrimental effects of synchronous xhrs

Author: awalGarg

snippets/showheaders/showheaders.js

@@ -5,17 +5,20 @@
 (function() {
 
   var request=new XMLHttpRequest();
-  request.open('HEAD',window.location,false);
-  request.send(null);
-
-  var headers = request.getAllResponseHeaders();
-  var tab = headers.split("\n").map(function(h) {
-    return { "Key": h.split(": ")[0], "Value": h.split(": ")[1] }
-  }).filter(function(h) { return h.Value !== undefined; });
+  request.open('HEAD',window.location,true);
+  
+  request.onload = request.onerror = function () {
+    var headers = request.getAllResponseHeaders();
+    var tab = headers.split("\n").map(function(h) {
+      return { "Key": h.split(": ")[0], "Value": h.split(": ")[1] }
+    }).filter(function(h) { return h.Value !== undefined; });
 
-  console.group("Request Headers");
-  console.log(headers);
-  console.table(tab);
-  console.groupEnd("Request Headers");
+    console.group("Request Headers");
+    console.log(headers);
+    console.table(tab);
+    console.groupEnd("Request Headers");
+  };
+  
+  request.send(null);
 
 })();