diff --git a/lib/js/Gruntfile.js b/lib/js/Gruntfile.js
index a2211fef94..a18d090fdf 100644
--- a/lib/js/Gruntfile.js
+++ b/lib/js/Gruntfile.js
@@ -307,12 +307,39 @@ module.exports = function (grunt) {
 
   grunt.registerTask(
     "wait",
-    "Wait just one second for the server to start",
+    "Wait until the test servers accept connections",
     function () {
       var done = this.async();
-      setTimeout(function () {
-        done(true);
-      }, 1000);
+      var net = require("net");
+      var ports = [8088, 8089, 8090, 8091];
+      var deadline = Date.now() + 30000;
+      var probe = function (index) {
+        if (index === ports.length) {
+          done(true);
+          return;
+        }
+        var socket = net.connect(ports[index], "localhost");
+        socket.on("connect", function () {
+          socket.destroy();
+          probe(index + 1);
+        });
+        socket.on("error", function () {
+          socket.destroy();
+          if (Date.now() < deadline) {
+            setTimeout(function () {
+              probe(index);
+            }, 100);
+          } else {
+            grunt.log.error(
+              "Nothing is listening on port " +
+                ports[index] +
+                " after 30 seconds",
+            );
+            done(false);
+          }
+        });
+      };
+      probe(0);
     },
   );
 
diff --git a/lib/ts/Gruntfile.js b/lib/ts/Gruntfile.js
index a13a6c4acc..49f85dc412 100644
--- a/lib/ts/Gruntfile.js
+++ b/lib/ts/Gruntfile.js
@@ -152,12 +152,39 @@ module.exports = function (grunt) {
 
   grunt.registerTask(
     "wait",
-    "Wait just one second for the server to start",
+    "Wait until the test server accepts connections",
     function () {
       var done = this.async();
-      setTimeout(function () {
-        done(true);
-      }, 1000);
+      var net = require("net");
+      var ports = [8089];
+      var deadline = Date.now() + 30000;
+      var probe = function (index) {
+        if (index === ports.length) {
+          done(true);
+          return;
+        }
+        var socket = net.connect(ports[index], "localhost");
+        socket.on("connect", function () {
+          socket.destroy();
+          probe(index + 1);
+        });
+        socket.on("error", function () {
+          socket.destroy();
+          if (Date.now() < deadline) {
+            setTimeout(function () {
+              probe(index);
+            }, 100);
+          } else {
+            grunt.log.error(
+              "Nothing is listening on port " +
+                ports[index] +
+                " after 30 seconds",
+            );
+            done(false);
+          }
+        });
+      };
+      probe(0);
     },
   );