9 files changed, 164 insertions, 2 deletions
diff --git a/dom/base/nsGkAtomList.h b/dom/base/nsGkAtomList.h
index 8fefa0e02..73a3a02b1 100644
--- a/dom/base/nsGkAtomList.h
+++ b/dom/base/nsGkAtomList.h
@@ -665,6 +665,7 @@ GK_ATOM(noembed, "noembed")
 GK_ATOM(noframes, "noframes")
 GK_ATOM(nohref, "nohref")
 GK_ATOM(noisolation, "noisolation")
+GK_ATOM(nomodule, "nomodule")
 GK_ATOM(nonce, "nonce")
 GK_ATOM(none, "none")
 GK_ATOM(noresize, "noresize")
diff --git a/dom/base/nsScriptLoader.cpp b/dom/base/nsScriptLoader.cpp
index 6f8251fc3..61d122386 100644
--- a/dom/base/nsScriptLoader.cpp
+++ b/dom/base/nsScriptLoader.cpp
@@ -1452,7 +1452,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
 
   nsCOMPtr<nsIContent> scriptContent = do_QueryInterface(aElement);
 
-  // Step 12. Check that the script is not an eventhandler
+  // Step 13. Check that the script is not an eventhandler
   if (IsScriptEventHandler(scriptContent)) {
     return false;
   }
@@ -1486,7 +1486,18 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
     }
   }
 
-  // Step 14. in the HTML5 spec
+  // "In modern user agents that support module scripts, the script element with
+  // the nomodule attribute will be ignored".
+  // "The nomodule attribute must not be specified on module scripts (and will
+  // be ignored if it is)."
+  if (ModuleScriptsEnabled() &&
+      scriptKind == nsScriptKind::Classic &&
+      scriptContent->IsHTMLElement() &&
+      scriptContent->HasAttr(kNameSpaceID_None, nsGkAtoms::nomodule)) {
+    return false;
+  }
+
+  // Step 15. and later in the HTML5 spec
   nsresult rv = NS_OK;
   RefPtr<nsScriptLoadRequest> request;
   if (aElement->GetScriptExternal()) {
diff --git a/dom/html/HTMLScriptElement.cpp b/dom/html/HTMLScriptElement.cpp
index 94d09c12c..095b9b77d 100644
--- a/dom/html/HTMLScriptElement.cpp
+++ b/dom/html/HTMLScriptElement.cpp
@@ -218,6 +218,18 @@ HTMLScriptElement::SetAsync(bool aValue, ErrorResult& rv)
   SetHTMLBoolAttr(nsGkAtoms::async, aValue, rv);
 }
 
+bool
+HTMLScriptElement::NoModule()
+{
+  return GetBoolAttr(nsGkAtoms::nomodule);
+}
+
+void
+HTMLScriptElement::SetNoModule(bool aValue, ErrorResult& aRv)
+{
+  SetHTMLBoolAttr(nsGkAtoms::nomodule, aValue, aRv);
+}
+
 nsresult
 HTMLScriptElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
                                 const nsAttrValue* aValue, bool aNotify)
diff --git a/dom/html/HTMLScriptElement.h b/dom/html/HTMLScriptElement.h
index 00628bd6d..19ceb414f 100644
--- a/dom/html/HTMLScriptElement.h
+++ b/dom/html/HTMLScriptElement.h
@@ -89,6 +89,8 @@ public:
   }
   bool Async();
   void SetAsync(bool aValue, ErrorResult& rv);
+  bool NoModule();
+  void SetNoModule(bool aValue, ErrorResult& rv);
 
 protected:
   virtual ~HTMLScriptElement();
diff --git a/dom/html/test/file_script_module.html b/dom/html/test/file_script_module.html
new file mode 100644
index 000000000..78c499265
--- /dev/null
+++ b/dom/html/test/file_script_module.html
@@ -0,0 +1,42 @@
+<html>
+<body>
+  <script>
+// Helper methods.
+function ok(a, msg) {
+  parent.postMessage({ check: !!a, msg }, "*")
+}
+
+function is(a, b, msg) {
+  ok(a === b, msg);
+}
+
+function finish() {
+  parent.postMessage({ done: true }, "*");
+}
+  </script>
+
+  <script id="a" nomodule>42</script>
+  <script id="b">42</script>
+  <script>
+// Let's test the behavior of nomodule attribute and noModule getter/setter.
+var a = document.getElementById("a");
+is(a.noModule, true, "HTMLScriptElement with nomodule attribute has noModule set to true");
+a.removeAttribute("nomodule");
+is(a.noModule, false, "HTMLScriptElement without nomodule attribute has noModule set to false");
+a.noModule = true;
+ok(a.hasAttribute('nomodule'), "HTMLScriptElement.noModule = true add the nomodule attribute");
+
+var b = document.getElementById("b");
+is(b.noModule, false, "HTMLScriptElement without nomodule attribute has noModule set to false");
+b.noModule = true;
+ok(b.hasAttribute('nomodule'), "HTMLScriptElement.noModule = true add the nomodule attribute");
+  </script>
+
+  <script>var foo = 42;</script>
+  <script nomodule>foo = 43;</script>
+  <script>
+is(foo, 42, "nomodule HTMLScriptElements should not be executed in modern browsers");
+finish();
+  </script>
+</body>
+</html>
diff --git a/dom/html/test/file_script_nomodule.html b/dom/html/test/file_script_nomodule.html
new file mode 100644
index 000000000..303edb90b
--- /dev/null
+++ b/dom/html/test/file_script_nomodule.html
@@ -0,0 +1,32 @@
+<html>
+<body>
+  <script>
+// Helper methods.
+function ok(a, msg) {
+  parent.postMessage({ check: !!a, msg }, "*")
+}
+
+function is(a, b, msg) {
+  ok(a === b, msg);
+}
+
+function finish() {
+  parent.postMessage({ done: true }, "*");
+}
+  </script>
+
+  <script id="a" nomodule>42</script>
+  <script>
+// Let's test the behavior of nomodule attribute and noModule getter/setter.
+var a = document.getElementById("a");
+ok(!("noModule" in a), "When modules are disabled HTMLScriptElement.noModule is not defined");
+  </script>
+
+  <script>var foo = 42;</script>
+  <script nomodule>foo = 43;</script>
+  <script>
+is(foo, 43, "nomodule attribute is ignored when modules are disabled");
+finish();
+  </script>
+</body>
+</html>
diff --git a/dom/html/test/mochitest.ini b/dom/html/test/mochitest.ini
index 99b425df8..0c0ba847c 100644
--- a/dom/html/test/mochitest.ini
+++ b/dom/html/test/mochitest.ini
@@ -606,3 +606,7 @@ skip-if = os == "android" # up/down arrow keys not supported on android
 [test_bug1295719_event_sequence_for_number_keys.html]
 [test_bug1310865.html]
 [test_bug1315146.html]
++[test_script_module.html]
++support-files =
++  file_script_module.html
++  file_script_nomodule.html
+\ No newline at end of file
diff --git a/dom/html/test/test_script_module.html b/dom/html/test/test_script_module.html
new file mode 100644
index 000000000..4878bb379
--- /dev/null
+++ b/dom/html/test/test_script_module.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for HTMLScriptElement with nomodule attribute</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+
+<body>
+  <script>
+onmessage = (e) => {
+  if ("done" in e.data) {
+    next();
+  } else if ("check" in e.data) {
+    ok(e.data.check, e.data.msg);
+  } else {
+    ok(false, "Unknown message");
+  }
+}
+
+var tests = [
+  function() {
+    SpecialPowers.pushPrefEnv({"set":[["dom.moduleScripts.enabled", true]]})
+    .then(() => {
+      var ifr = document.createElement('iframe');
+      ifr.src = "file_script_module.html";
+      document.body.appendChild(ifr);
+    });
+  },
+
+  function() {
+    SpecialPowers.pushPrefEnv({"set":[["dom.moduleScripts.enabled", false]]})
+    .then(() => {
+      var ifr = document.createElement('iframe');
+      ifr.src = "file_script_nomodule.html";
+      document.body.appendChild(ifr);
+    });
+  },
+];
+
+SimpleTest.waitForExplicitFinish();
+next();
+
+function next() {
+  if (!tests.length) {
+    SimpleTest.finish();
+    return;
+  }
+
+  var test = tests.shift();
+  test();
+}
+  </script>
+
+</body>
+</html>
diff --git a/dom/webidl/HTMLScriptElement.webidl b/dom/webidl/HTMLScriptElement.webidl
index 377056366..5b64c42d7 100644
--- a/dom/webidl/HTMLScriptElement.webidl
+++ b/dom/webidl/HTMLScriptElement.webidl
@@ -13,6 +13,8 @@ interface HTMLScriptElement : HTMLElement {
   attribute DOMString src;
   [SetterThrows]
   attribute DOMString type;
+  [SetterThrows, Pref="dom.moduleScripts.enabled"]
+  attribute boolean noModule;
   [SetterThrows]
   attribute DOMString charset;
   [SetterThrows]