--- a/browser/base/content/test/static/browser_all_files_referenced.js
+++ b/browser/base/content/test/static/browser_all_files_referenced.js
@@ -638,20 +638,16 @@ add_task(async function checkAllTheFiles
     }
 
     return true;
   });
 
   // Wait for all manifest to be parsed
   await throttledMapPromises(manifestURIs, parseManifest);
 
-  for (let jsm of Components.manager.getComponentJSMs()) {
-    gReferencesFromCode.set(jsm, null);
-  }
-
   // manifest.json is a common name, it is used for WebExtension manifests
   // but also for other things.  To tell them apart, we have to actually
   // read the contents.  This will populate gExtensionRoots with all
   // embedded extension APIs, and return any manifest.json files that aren't
   // webextensions.
   let nonWebextManifests = (await Promise.all(jsonManifests.map(parseJsonManifest)))
                                          .filter(uri => !!uri);
   uris.push(...nonWebextManifests);

--- a/build/docs/defining-xpcom-components.rst
+++ b/build/docs/defining-xpcom-components.rst
@@ -97,22 +97,16 @@ Class definitions may have the following
   The fully-qualified name of a constructor function to call in order to
   create instances of this class. This function must be declared in one of the
   headers listed in the ``headers`` property, must take no arguments, and must
   return ``already_AddRefed<iface>`` where ``iface`` is the interface provided
   in the ``type`` property.
   
   This property is incompatible with ``legacy_constructor``.
 
-``jsm`` (optional)
-  If provided, must be the URL of a JavaScript module which contains a
-  JavaScript implementation of the component. The ``constructor`` property
-  must contain the name of an exported function which can be constructed to
-  create a new instance of the component.
-
 ``legacy_constructor`` (optional)
   This property is deprecated, and should not be used in new code.
   
   The fully-qualified name of a constructor function to call in order to
   create instances of this class. This function must be declared in one of the
   headers listed in the ``headers`` property, and must have the signature
   ``nsresult(nsISupports* aOuter, const nsID& aIID, void** aResult)``, and
   behave equivalently to ``nsIFactory::CreateInstance``.

--- a/xpcom/components/StaticComponents.cpp.in
+++ b/xpcom/components/StaticComponents.cpp.in
@@ -4,42 +4,34 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "StaticComponents.h"
 
 #include "mozilla/PerfectHash.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/StaticPtr.h"
-#include "mozilla/UniquePtr.h"
-#include "mozilla/dom/ScriptSettings.h"
-#include "mozJSComponentLoader.h"
 #include "nsCOMPtr.h"
 #include "nsComponentManager.h"
-#include "nsContentUtils.h"
 #include "nsIFactory.h"
 #include "nsISupports.h"
 #include "nsString.h"
-#include "nsStringEnumerator.h"
 
 // Cleanup pollution from zipstruct.h
 #undef UNSUPPORTED
 
 // Public includes
 //# @includes@
 
 // Relative includes
 //# @relative_includes@
 
 //# @decls@
 
 namespace mozilla {
-
-using dom::AutoJSAPI;
-
 namespace xpcom {
 
 static constexpr uint32_t kNoContractID = 0xffffffff;
 
 namespace {
 // Template helpers for constructor function sanity checks.
 template <typename T>
 struct RemoveAlreadyAddRefed {
@@ -65,20 +57,16 @@ static const char gStrings[] =
 
 const StaticCategory gStaticCategories[kStaticCategoryCount] = {
 //# @categories@
 };
 const StaticCategoryEntry gStaticCategoryEntries[] = {
 //# @category_entries@
 };
 
-const StringOffset gComponentJSMs[] = {
-//# @component_jsms@
-};
-
 /**
  * Returns a nsCString corresponding to the given entry in the `gStrings` string
  * table. The resulting nsCString points directly to static storage, and does
  * not incur any memory allocation overhead.
  */
 static inline nsCString GetString(const StringOffset& aOffset) {
   const char* str = &gStrings[aOffset.mOffset];
   nsCString result;
@@ -90,47 +78,16 @@ nsCString ContractEntry::ContractID() co
   return GetString(mContractID);
 }
 
 bool ContractEntry::Matches(const nsACString& aContractID) const {
   return aContractID == ContractID() && Module().Active();
 }
 
 
-static nsresult ConstructJSMComponent(const nsACString& aURI,
-                                      const char* aConstructor,
-                                      nsISupports** aResult) {
-  if (!nsComponentManagerImpl::JSLoaderReady()) {
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
-  AutoJSAPI jsapi;
-  MOZ_ALWAYS_TRUE(jsapi.Init(xpc::PrivilegedJunkScope()));
-  JSContext* cx = jsapi.cx();
-
-  JS::RootedObject global(cx);
-  JS::RootedObject exports(cx);
-  MOZ_TRY(mozJSComponentLoader::Get()->Import(cx, aURI, &global, &exports));
-
-  JS::RootedValue ctor(cx);
-  if (!JS_GetProperty(cx, exports, aConstructor, &ctor) ||
-      !ctor.isObject()) {
-    return NS_ERROR_XPC_JSOBJECT_HAS_NO_FUNCTION_NAMED;
-  }
-
-  JS::RootedObject inst(cx);
-  if (!JS::Construct(cx, ctor, JS::HandleValueArray::empty(), &inst)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  return nsContentUtils::XPConnect()->WrapJS(cx, inst, NS_GET_IID(nsISupports),
-                                             (void**)aResult);
-}
-
-
 //# @module_cid_table@
 
 //# @module_contract_id_table@
 
 static inline bool CalledInit(size_t aIdx) {
   return GetBit(gInitCalled, aIdx);
 }
 
@@ -269,30 +226,16 @@ nsCString StaticCategory::Name() const {
     const nsACString& aContractID, bool aInvalid) {
   if (const ContractEntry* entry = LookupContractID(aContractID)) {
     entry->SetInvalid(aInvalid);
     return true;
   }
   return false;
 }
 
-/* static */ already_AddRefed<nsIUTF8StringEnumerator>
-StaticComponents::GetComponentJSMs() {
-  auto jsms = MakeUnique<nsTArray<nsCString>>(MOZ_ARRAY_LENGTH(gComponentJSMs));
-
-  for (const auto& entry : gComponentJSMs) {
-    jsms->AppendElement(GetString(entry));
-  }
-
-  nsCOMPtr<nsIUTF8StringEnumerator> result;
-  MOZ_ALWAYS_SUCCEEDS(NS_NewAdoptingUTF8StringEnumerator(getter_AddRefs(result),
-                                                         jsms.release()));
-  return result.forget();
-}
-
 /* static */ void StaticComponents::Shutdown() {
   CallUnloadFuncs();
 }
 
 /* static */ const nsID& Components::GetCID(ModuleID aID) {
   return gStaticModules[size_t(aID)].CID();
 }
 

--- a/xpcom/components/StaticComponents.h
+++ b/xpcom/components/StaticComponents.h
@@ -12,17 +12,16 @@
 #include "nsID.h"
 #include "nsStringFwd.h"
 #include "nscore.h"
 
 #include "mozilla/Components.h"
 #include "StaticComponentData.h"
 
 class nsIFactory;
-class nsIUTF8StringEnumerator;
 class nsISupports;
 
 namespace mozilla {
 namespace xpcom {
 
 struct ContractEntry;
 struct StaticModule;
 
@@ -204,18 +203,16 @@ class StaticComponents final {
 
   /**
    * Marks a static contract ID entry invalid (or unsets the invalid bit if
    * aInvalid is false). See `CategoryEntry::Invalid()`.
    */
   static bool InvalidateContractID(const nsACString& aContractID,
                                    bool aInvalid = true);
 
-  static already_AddRefed<nsIUTF8StringEnumerator> GetComponentJSMs();
-
   /**
    * Calls any module unload from manifests whose components have been loaded.
    */
   static void Shutdown();
 };
 
 }  // namespace xpcom
 }  // namespace mozilla

--- a/xpcom/components/gen_static_components.py
+++ b/xpcom/components/gen_static_components.py
@@ -213,18 +213,16 @@ class ModuleEntry(object):
         # `CallInitFunc(init_idx)` call will be genrated before calling this
         # module's constructor.
         self.init_idx = init_idx
 
         self.constructor = data.get('constructor', None)
         self.legacy_constructor = data.get('legacy_constructor', None)
         self.init_method = data.get('init_method', [])
 
-        self.jsm = data.get('jsm', None)
-
         self.external = data.get('external', not (self.headers or
                                                   self.legacy_constructor))
         self.singleton = data.get('singleton', False)
         self.overridable = data.get('overridable', False)
 
         if 'name' in data:
             self.anonymous = False
             self.name = data['name']
@@ -233,25 +231,17 @@ class ModuleEntry(object):
             self.name = 'Anonymous%03d' % ModuleEntry.next_anon_id
             ModuleEntry.next_anon_id += 1
 
         def error(str_):
             raise Exception("Error defining component %s (%s): %s" % (
                 str(self.cid), ', '.join(map(repr, self.contract_ids)),
                 str_))
 
-        if self.jsm:
-            if not self.constructor:
-                error("JavaScript components must specify a constructor")
-
-            for prop in ('init_method', 'legacy_constructor', 'headers'):
-                if getattr(self, prop):
-                    error("JavaScript components may not specify a '%s' "
-                          "property" % prop)
-        elif self.external:
+        if self.external:
             if self.constructor or self.legacy_constructor:
                 error("Externally-constructed components may not specify "
                       "'constructor' or 'legacy_constructor' properties")
             if self.init_method:
                 error("Externally-constructed components may not specify "
                       "'init_method' properties")
             if self.type == 'nsISupports':
                 error("Externally-constructed components must specify a type "
@@ -304,24 +294,17 @@ class ModuleEntry(object):
         if self.init_idx is not None:
             res += '      MOZ_TRY(CallInitFunc(%d));\n' % self.init_idx
 
         if self.legacy_constructor:
             res += ('      return /* legacy */ %s(nullptr, aIID, aResult);\n'
                     % self.legacy_constructor)
             return res
 
-        if self.jsm:
-            res += (
-                '      nsCOMPtr<nsISupports> inst;\n'
-                '      MOZ_TRY(ConstructJSMComponent(NS_LITERAL_CSTRING(%s),\n'
-                '                                    %s,\n'
-                '                                    getter_AddRefs(inst)));'
-                '\n' % (json.dumps(self.jsm), json.dumps(self.constructor)))
-        elif self.external:
+        if self.external:
             res += ('      nsCOMPtr<nsISupports> inst = '
                     'mozCreateComponent<%s>();\n' % self.type)
         else:
             res += '      RefPtr<%s> inst = ' % self.type
 
             if not self.constructor:
                 res += 'new %s();\n' % self.type
             else:
@@ -562,18 +545,16 @@ def gen_substs(manifests):
 
         for clas in manifest['Classes']:
             modules.append(ModuleEntry(clas, init_idx))
 
     contracts = []
     contract_map = {}
     categories = defaultdict(list)
 
-    jsms = set()
-
     types = set()
 
     for mod in modules:
         headers |= set(mod.headers)
 
         for contract_id in mod.contract_ids:
             if contract_id in contract_map:
                 raise Exception('Duplicate contract ID: %s' % contract_id)
@@ -585,19 +566,16 @@ def gen_substs(manifests):
         for category, entries in mod.categories.items():
             for entry in to_list(entries):
                 categories[category].append((entry, mod.contract_id,
                                              mod.processes))
 
         if mod.type and not mod.headers:
             types.add(mod.type)
 
-        if mod.jsm:
-            jsms.add(mod.jsm)
-
     cid_phf = PerfectHash(modules, PHF_SIZE,
                           key=lambda module: module.cid.bytes)
 
     contract_phf = PerfectHash(contracts, PHF_SIZE,
                                key=lambda entry: entry.contract)
 
     substs = {}
 
@@ -608,19 +586,16 @@ def gen_substs(manifests):
 
     substs['module_count'] = len(modules)
     substs['contract_count'] = len(contracts)
 
     gen_module_funcs(substs, module_funcs)
 
     gen_includes(substs, headers)
 
-    substs['component_jsms'] = '\n'.join(' %s,' % strings.entry_to_cxx(jsm)
-                                         for jsm in sorted(jsms)) + '\n'
-
     substs['decls'] = gen_decls(types)
 
     substs['constructors'] = gen_constructors(cid_phf.entries)
 
     substs['component_getters'] = gen_getters(cid_phf.entries)
 
     substs['module_cid_table'] = cid_phf.cxx_codegen(
         name='ModuleByCID',

--- a/xpcom/components/nsComponentManager.cpp
+++ b/xpcom/components/nsComponentManager.cpp
@@ -526,18 +526,16 @@ nsresult nsComponentManagerImpl::Init() 
       break;
   }
 
   if (loadChromeManifests) {
     // This needs to be called very early, before anything in nsLayoutModule is
     // used, and before any calls are made into the JS engine.
     nsLayoutModuleInitialize();
 
-    mJSLoaderReady = true;
-
     // The overall order in which chrome.manifests are expected to be treated
     // is the following:
     // - greDir
     // - greDir's omni.ja
     // - appDir
     // - appDir's omni.ja
 
     InitializeModuleLocations();
@@ -2007,24 +2005,16 @@ nsComponentManagerImpl::RemoveBootstrapp
   // Remove reference.
   nsComponentManagerImpl::sModuleLocations->RemoveElement(
       elem, ComponentLocationComparator());
 
   rv = cr->CheckForNewChrome();
   return rv;
 }
 
-
-NS_IMETHODIMP
-nsComponentManagerImpl::GetComponentJSMs(nsIUTF8StringEnumerator** aJSMs) {
-  nsCOMPtr<nsIUTF8StringEnumerator> result = StaticComponents::GetComponentJSMs();
-  result.forget(aJSMs);
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsComponentManagerImpl::GetManifestLocations(nsIArray** aLocations) {
   NS_ENSURE_ARG_POINTER(aLocations);
   *aLocations = nullptr;
 
   if (!sModuleLocations) {
     return NS_ERROR_NOT_INITIALIZED;
   }

--- a/xpcom/components/nsComponentManager.h
+++ b/xpcom/components/nsComponentManager.h
@@ -161,18 +161,16 @@ class nsComponentManagerImpl final : pub
   mozilla::Maybe<EntryWrapper> LookupByContractID(
       const nsACString& aContractID);
   mozilla::Maybe<EntryWrapper> LookupByContractID(
       const MutexLock&, const nsACString& aContractID);
 
   nsresult GetService(mozilla::xpcom::ModuleID, const nsIID& aIID,
                       void** aResult);
 
-  static bool JSLoaderReady() { return gComponentManager->mJSLoaderReady; }
-
   static void InitializeStaticModules();
   static void InitializeModuleLocations();
 
   struct ComponentLocation {
     NSLocationType type;
     mozilla::FileLocation location;
   };
 
@@ -278,18 +276,16 @@ class nsComponentManagerImpl final : pub
 
   inline PendingServiceInfo* AddPendingService(const nsCID& aServiceCID,
                                                PRThread* aThread);
   inline void RemovePendingService(const nsCID& aServiceCID);
   inline PRThread* GetPendingServiceThread(const nsCID& aServiceCID) const;
 
   nsTArray<PendingServiceInfo> mPendingServices;
 
-  bool mJSLoaderReady = false;
-
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 
  private:
   ~nsComponentManagerImpl();
 
   nsresult GetServiceLocked(MutexLock& aLock, EntryWrapper& aEntry,
                             const nsIID& aIID, void** aResult);
 };

--- a/xpcom/components/nsIComponentManager.idl
+++ b/xpcom/components/nsIComponentManager.idl
@@ -7,17 +7,16 @@
  * The nsIComponentManager interface.
  */
 
 #include "nsISupports.idl"
 
 interface nsIFile;
 interface nsIFactory;
 interface nsIArray;
-interface nsIUTF8StringEnumerator;
 
 [scriptable, uuid(d604ffc3-1ba3-4f6c-b65f-1ed4199364c3)]
 interface nsIComponentManager : nsISupports
 {
     /**
      * getClassObject
      *
      * Returns the factory object that can be used to create instances of
@@ -92,22 +91,16 @@ interface nsIComponentManager : nsISuppo
     void removeBootstrappedManifestLocation(in nsIFile aLocation);
 
     /**
      * getManifestLocations
      *
      * Get an array of nsIURIs of all registered and builtin manifest locations.
      */
     nsIArray getManifestLocations();
-
-    /**
-     * Returns a list of JSM URLs which are used to create components. This
-     * should only be used in automation.
-     */
-    nsIUTF8StringEnumerator getComponentJSMs();
 };
 
 
 %{ C++
 #ifdef MOZILLA_INTERNAL_API
 #include "nsComponentManagerUtils.h"
 #endif
 %} C++