diff --git a/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java b/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
index f7c66026e..99aa1180c 100644
--- a/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
+++ b/core/src/main/java/org/teavm/backend/javascript/JavaScriptTarget.java
@@ -30,8 +30,10 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 import java.util.Set;
 import java.util.function.Function;
 import org.teavm.ast.AsyncMethodNode;
@@ -50,11 +52,14 @@ import org.teavm.backend.javascript.decompile.PreparedClass;
 import org.teavm.backend.javascript.decompile.PreparedMethod;
 import org.teavm.backend.javascript.rendering.Renderer;
 import org.teavm.backend.javascript.rendering.RenderingContext;
+import org.teavm.backend.javascript.rendering.RenderingUtil;
 import org.teavm.backend.javascript.rendering.RuntimeRenderer;
 import org.teavm.backend.javascript.spi.GeneratedBy;
 import org.teavm.backend.javascript.spi.Generator;
 import org.teavm.backend.javascript.spi.InjectedBy;
 import org.teavm.backend.javascript.spi.Injector;
+import org.teavm.backend.javascript.spi.ModuleImporter;
+import org.teavm.backend.javascript.spi.ModuleImporterContext;
 import org.teavm.backend.javascript.spi.VirtualMethodContributor;
 import org.teavm.backend.javascript.spi.VirtualMethodContributorContext;
 import org.teavm.cache.AstCacheEntry;
@@ -68,6 +73,7 @@ import org.teavm.debugging.information.SourceLocation;
 import org.teavm.dependency.AbstractDependencyListener;
 import org.teavm.dependency.DependencyAgent;
 import org.teavm.dependency.DependencyAnalyzer;
+import org.teavm.dependency.DependencyInfo;
 import org.teavm.dependency.DependencyListener;
 import org.teavm.dependency.DependencyType;
 import org.teavm.dependency.MethodDependency;
@@ -83,6 +89,7 @@ import org.teavm.model.ClassReaderSource;
 import org.teavm.model.ElementModifier;
 import org.teavm.model.FieldReference;
 import org.teavm.model.ListableClassHolderSource;
+import org.teavm.model.ListableClassReaderSource;
 import org.teavm.model.MethodHolder;
 import org.teavm.model.MethodReader;
 import org.teavm.model.MethodReference;
@@ -120,6 +127,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
     private final Map<MethodReference, Injector> methodInjectors = new HashMap<>();
     private final List<Function<ProviderContext, Generator>> generatorProviders = new ArrayList<>();
     private final List<Function<ProviderContext, Injector>> injectorProviders = new ArrayList<>();
+    private final List<Function<ProviderContext, ModuleImporter>> moduleImporterProviders = new ArrayList<>();
     private final List<RendererListener> rendererListeners = new ArrayList<>();
     private DebugInformationEmitter debugEmitter;
     private MethodNodeCache astCache = EmptyMethodNodeCache.INSTANCE;
@@ -131,6 +139,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
     private boolean strict;
     private BoundCheckInsertion boundCheckInsertion = new BoundCheckInsertion();
     private NullCheckInsertion nullCheckInsertion = new NullCheckInsertion(NullCheckFilter.EMPTY);
+    private final Map<String, String> importedModules = new LinkedHashMap<>();
 
     @Override
     public List<ClassHolderTransformer> getTransformers() {
@@ -172,6 +181,11 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
         injectorProviders.add(provider);
     }
 
+    @Override
+    public void addModuleImporterProvider(Function<ProviderContext, ModuleImporter> provider) {
+        moduleImporterProviders.add(provider);
+    }
+
     /**
      * Specifies whether this TeaVM instance uses obfuscation when generating the JavaScript code.
      *
@@ -361,6 +375,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
 
     private void emit(ListableClassHolderSource classes, Writer writer, BuildTarget target) {
         List<PreparedClass> clsNodes = modelToAst(classes);
+        prepareModules(classes);
         if (controller.wasCancelled()) {
             return;
         }
@@ -382,7 +397,13 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
                 controller.getUnprocessedClassSource(), classes,
                 controller.getClassLoader(), controller.getServices(), controller.getProperties(), naming,
                 controller.getDependencyInfo(), m -> isVirtual(virtualMethodContributorContext, m),
-                controller.getClassInitializerInfo(), strict);
+                controller.getClassInitializerInfo(), strict
+        ) {
+            @Override
+            public String importModule(String name) {
+                return JavaScriptTarget.this.importModule(name);
+            }
+        };
         renderingContext.setMinifying(obfuscated);
         Renderer renderer = new Renderer(sourceWriter, asyncMethods, asyncFamilyMethods,
                 controller.getDiagnostics(), renderingContext);
@@ -404,7 +425,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
             renderer.setDebugEmitter(debugEmitter);
         }
         renderer.getDebugEmitter().setLocationProvider(sourceWriter);
-        for (Map.Entry<MethodReference, Injector> entry : methodInjectors.entrySet()) {
+        for (var entry : methodInjectors.entrySet()) {
             renderingContext.addInjector(entry.getKey(), entry.getValue());
         }
         try {
@@ -462,21 +483,45 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
     private void printWrapperStart(SourceWriter writer) throws IOException {
         writer.append("\"use strict\";").newLine();
         printUmdStart(writer);
-        writer.append("function($rt_globals,").ws().append("$rt_exports)").appendBlockStart();
+        writer.append("function($rt_globals,").ws().append("$rt_exports");
+        for (var moduleName : importedModules.values()) {
+            writer.append(",").ws().appendFunction(moduleName);
+        }
+        writer.append(")").appendBlockStart();
+    }
+
+    private String importModule(String name) {
+        return importedModules.get(name);
     }
 
     private void printUmdStart(SourceWriter writer) throws IOException {
         writer.append("(function(root,").ws().append("module)").appendBlockStart();
         writer.appendIf().append("typeof define").ws().append("===").ws().append("'function'")
                 .ws().append("&&").ws().append("define.amd)").appendBlockStart();
-        writer.append("define(['exports'],").ws().append("function(exports)").ws().appendBlockStart();
-        writer.append("module(root,").ws().append("exports);").softNewLine();
+        writer.append("define(['exports'");
+        for (var moduleName : importedModules.keySet()) {
+            writer.append(',').ws().append('"').append(RenderingUtil.escapeString(moduleName)).append('"');
+        }
+        writer.append("],").ws().append("function(exports");
+        for (var moduleAlias : importedModules.values()) {
+            writer.append(',').ws().appendFunction(moduleAlias);
+        }
+        writer.append(")").ws().appendBlockStart();
+        writer.append("module(root,").ws().append("exports");
+        for (var moduleAlias : importedModules.values()) {
+            writer.append(',').ws().appendFunction(moduleAlias);
+        }
+        writer.append(");").softNewLine();
         writer.outdent().append("});").softNewLine();
 
         writer.appendElseIf().append("typeof exports").ws()
                 .append("===").ws().append("'object'").ws().append("&&").ws()
                 .append("typeof exports.nodeName").ws().append("!==").ws().append("'string')").appendBlockStart();
-        writer.append("module(global,").ws().append("exports);").softNewLine();
+        writer.append("module(global,").ws().append("exports");
+        for (var moduleName : importedModules.keySet()) {
+            writer.append(',').ws().append("require(\"").append(RenderingUtil.escapeString(moduleName)).append("\")");
+        }
+        writer.append(");").softNewLine();
 
         writer.appendElse();
         writer.append("module(root,").ws().append("root);").softNewLine();
@@ -519,6 +564,28 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
         return STATS_NUM_FORMAT.format(size) + " (" + STATS_PERCENT_FORMAT.format((double) size / totalSize) + ")";
     }
 
+    private void prepareModules(ListableClassHolderSource classes) {
+        var context = new ImporterContext(classes);
+        for (var className : classes.getClassNames()) {
+            var cls = classes.get(className);
+            for (var method : cls.getMethods()) {
+                if (method.getModifiers().contains(ElementModifier.ABSTRACT)) {
+                    continue;
+                }
+
+                var providerContext = new ProviderContextImpl(method.getReference());
+                for (var provider : moduleImporterProviders) {
+                    var importer = provider.apply(providerContext);
+                    if (importer != null) {
+                        context.method = method;
+                        importer.importModules(context);
+                        context.method = null;
+                    }
+                }
+            }
+        }
+    }
+
     private List<PreparedClass> modelToAst(ListableClassHolderSource classes) {
         AsyncMethodFinder asyncFinder = new AsyncMethodFinder(controller.getDependencyInfo().getCallGraph(),
                 controller.getDependencyInfo());
@@ -676,7 +743,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
 
         boolean found = false;
         ProviderContext context = new ProviderContextImpl(method.getReference());
-        for (Function<ProviderContext, Generator> provider : generatorProviders) {
+        for (var provider : generatorProviders) {
             Generator generator = provider.apply(context);
             if (generator != null) {
                 methodGenerators.put(method.getReference(), generator);
@@ -684,7 +751,7 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
                 break;
             }
         }
-        for (Function<ProviderContext, Injector> provider : injectorProviders) {
+        for (var provider : injectorProviders) {
             Injector injector = provider.apply(context);
             if (injector != null) {
                 methodInjectors.put(method.getReference(), injector);
@@ -756,6 +823,11 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
         public ClassReaderSource getClassSource() {
             return controller.getUnprocessedClassSource();
         }
+
+        @Override
+        public <T> T getService(Class<T> type) {
+            return controller.getServices().getService(type);
+        }
     }
 
     @PlatformMarker
@@ -820,4 +892,48 @@ public class JavaScriptTarget implements TeaVMTarget, TeaVMJavaScriptHost {
             return classSource;
         }
     }
+
+    class ImporterContext implements ModuleImporterContext {
+        private ListableClassReaderSource classSource;
+        MethodReader method;
+
+        ImporterContext(ListableClassReaderSource classSource) {
+            this.classSource = classSource;
+        }
+
+        @Override
+        public MethodReader getMethod() {
+            return method;
+        }
+
+        @Override
+        public void importModule(String name) {
+            importedModules.computeIfAbsent(name, n -> "$rt_import_" + importedModules.size());
+        }
+
+        @Override
+        public ListableClassReaderSource getClassSource() {
+            return classSource;
+        }
+
+        @Override
+        public ClassLoader getClassLoader() {
+            return controller.getClassLoader();
+        }
+
+        @Override
+        public Properties getProperties() {
+            return JavaScriptTarget.this.controller.getProperties();
+        }
+
+        @Override
+        public DependencyInfo getDependency() {
+            return controller.getDependencyInfo();
+        }
+
+        @Override
+        public <T> T getService(Class<T> type) {
+            return controller.getServices().getService(type);
+        }
+    }
 }
diff --git a/core/src/main/java/org/teavm/backend/javascript/ProviderContext.java b/core/src/main/java/org/teavm/backend/javascript/ProviderContext.java
index 4712fa8ae..aa8eeba01 100644
--- a/core/src/main/java/org/teavm/backend/javascript/ProviderContext.java
+++ b/core/src/main/java/org/teavm/backend/javascript/ProviderContext.java
@@ -15,10 +15,11 @@
  */
 package org.teavm.backend.javascript;
 
+import org.teavm.common.ServiceRepository;
 import org.teavm.model.ClassReaderSource;
 import org.teavm.model.MethodReference;
 
-public interface ProviderContext {
+public interface ProviderContext extends ServiceRepository {
     MethodReference getMethod();
 
     ClassReaderSource getClassSource();
diff --git a/core/src/main/java/org/teavm/backend/javascript/TeaVMJavaScriptHost.java b/core/src/main/java/org/teavm/backend/javascript/TeaVMJavaScriptHost.java
index d7684fee5..381f1e686 100644
--- a/core/src/main/java/org/teavm/backend/javascript/TeaVMJavaScriptHost.java
+++ b/core/src/main/java/org/teavm/backend/javascript/TeaVMJavaScriptHost.java
@@ -18,6 +18,7 @@ package org.teavm.backend.javascript;
 import java.util.function.Function;
 import org.teavm.backend.javascript.spi.Generator;
 import org.teavm.backend.javascript.spi.Injector;
+import org.teavm.backend.javascript.spi.ModuleImporter;
 import org.teavm.backend.javascript.spi.VirtualMethodContributor;
 import org.teavm.model.MethodReference;
 import org.teavm.vm.spi.RendererListener;
@@ -32,6 +33,8 @@ public interface TeaVMJavaScriptHost extends TeaVMHostExtension {
 
     void addInjectorProvider(Function<ProviderContext, Injector> provider);
 
+    void addModuleImporterProvider(Function<ProviderContext, ModuleImporter> provider);
+
     void add(RendererListener listener);
 
     void addVirtualMethods(VirtualMethodContributor virtualMethods);
diff --git a/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java b/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
index f2cc4e754..1e45d4632 100644
--- a/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
+++ b/core/src/main/java/org/teavm/backend/javascript/rendering/Renderer.java
@@ -1212,6 +1212,11 @@ public class Renderer implements RenderingManager {
         public boolean isDynamicInitializer(String className) {
             return context.isDynamicInitializer(className);
         }
+
+        @Override
+        public String importModule(String name) {
+            return context.importModule(name);
+        }
     }
 
     private void appendMonitor(StatementRenderer statementRenderer, MethodNode methodNode) throws IOException {
diff --git a/core/src/main/java/org/teavm/backend/javascript/rendering/RenderingContext.java b/core/src/main/java/org/teavm/backend/javascript/rendering/RenderingContext.java
index 17b8dbc62..f82751ef5 100644
--- a/core/src/main/java/org/teavm/backend/javascript/rendering/RenderingContext.java
+++ b/core/src/main/java/org/teavm/backend/javascript/rendering/RenderingContext.java
@@ -47,7 +47,7 @@ import org.teavm.model.TextLocation;
 import org.teavm.model.ValueType;
 import org.teavm.model.analysis.ClassInitializerInfo;
 
-public class RenderingContext {
+public abstract class RenderingContext {
     private final DebugInformationEmitter debugEmitter;
     private ClassReaderSource initialClassSource;
     private ListableClassReaderSource classSource;
@@ -406,6 +406,8 @@ public class RenderingContext {
         return strict;
     }
 
+    public abstract String importModule(String name);
+
     @PlatformMarker
     private static boolean isBootstrap() {
         return false;
diff --git a/core/src/main/java/org/teavm/backend/javascript/rendering/StatementRenderer.java b/core/src/main/java/org/teavm/backend/javascript/rendering/StatementRenderer.java
index eb87f6d67..0f65b6c2e 100644
--- a/core/src/main/java/org/teavm/backend/javascript/rendering/StatementRenderer.java
+++ b/core/src/main/java/org/teavm/backend/javascript/rendering/StatementRenderer.java
@@ -1747,5 +1747,10 @@ public class StatementRenderer implements ExprVisitor, StatementVisitor {
         public ListableClassReaderSource getClassSource() {
             return context.getClassSource();
         }
+
+        @Override
+        public String importModule(String name) {
+            return context.importModule(name);
+        }
     }
 }
diff --git a/core/src/main/java/org/teavm/backend/javascript/spi/GeneratorContext.java b/core/src/main/java/org/teavm/backend/javascript/spi/GeneratorContext.java
index fb612fde5..256a1b394 100644
--- a/core/src/main/java/org/teavm/backend/javascript/spi/GeneratorContext.java
+++ b/core/src/main/java/org/teavm/backend/javascript/spi/GeneratorContext.java
@@ -28,6 +28,8 @@ import org.teavm.model.ValueType;
 public interface GeneratorContext extends ServiceRepository {
     String getParameterName(int index);
 
+    String importModule(String name);
+
     ClassReaderSource getInitialClassSource();
 
     ListableClassReaderSource getClassSource();
diff --git a/core/src/main/java/org/teavm/backend/javascript/spi/InjectorContext.java b/core/src/main/java/org/teavm/backend/javascript/spi/InjectorContext.java
index 16f318fb0..8facb3ec9 100644
--- a/core/src/main/java/org/teavm/backend/javascript/spi/InjectorContext.java
+++ b/core/src/main/java/org/teavm/backend/javascript/spi/InjectorContext.java
@@ -27,6 +27,8 @@ import org.teavm.model.ValueType;
 public interface InjectorContext extends ServiceRepository {
     Expr getArgument(int index);
 
+    String importModule(String name);
+
     int argumentCount();
 
     boolean isMinifying();
diff --git a/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporter.java b/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporter.java
new file mode 100644
index 000000000..a478e6447
--- /dev/null
+++ b/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporter.java
@@ -0,0 +1,20 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.javascript.spi;
+
+public interface ModuleImporter {
+    void importModules(ModuleImporterContext context);
+}
diff --git a/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporterContext.java b/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporterContext.java
new file mode 100644
index 000000000..bab706e59
--- /dev/null
+++ b/core/src/main/java/org/teavm/backend/javascript/spi/ModuleImporterContext.java
@@ -0,0 +1,36 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.javascript.spi;
+
+import java.util.Properties;
+import org.teavm.common.ServiceRepository;
+import org.teavm.dependency.DependencyInfo;
+import org.teavm.model.ListableClassReaderSource;
+import org.teavm.model.MethodReader;
+
+public interface ModuleImporterContext extends ServiceRepository {
+    MethodReader getMethod();
+
+    void importModule(String name);
+
+    ListableClassReaderSource getClassSource();
+
+    ClassLoader getClassLoader();
+
+    Properties getProperties();
+
+    DependencyInfo getDependency();
+}
diff --git a/core/src/main/java/org/teavm/model/analysis/BaseTypeInference.java b/core/src/main/java/org/teavm/model/analysis/BaseTypeInference.java
index 744040ad0..0684b4d39 100644
--- a/core/src/main/java/org/teavm/model/analysis/BaseTypeInference.java
+++ b/core/src/main/java/org/teavm/model/analysis/BaseTypeInference.java
@@ -106,7 +106,7 @@ public abstract class BaseTypeInference<T> {
                 continue;
             }
             type = doMerge(type, formerType);
-            if (Objects.equals(type, formerType)) {
+            if (Objects.equals(type, formerType) || type == null) {
                 continue;
             }
             types[variable] = type;
diff --git a/jso/core/src/main/java/org/teavm/jso/JSBody.java b/jso/core/src/main/java/org/teavm/jso/JSBody.java
index 862e91485..5df77b27a 100644
--- a/jso/core/src/main/java/org/teavm/jso/JSBody.java
+++ b/jso/core/src/main/java/org/teavm/jso/JSBody.java
@@ -133,4 +133,6 @@ public @interface JSBody {
      * <p>JavaScript code.</p>
      */
     String script();
+
+    JSBodyImport[] imports() default {};
 }
diff --git a/jso/core/src/main/java/org/teavm/jso/JSBodyImport.java b/jso/core/src/main/java/org/teavm/jso/JSBodyImport.java
new file mode 100644
index 000000000..af8aaa558
--- /dev/null
+++ b/jso/core/src/main/java/org/teavm/jso/JSBodyImport.java
@@ -0,0 +1,26 @@
+/*
+ *  Copyright 2023 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.jso;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.CLASS)
+public @interface JSBodyImport {
+    String alias();
+
+    String fromModule();
+}
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/Imports.java b/jso/impl/src/main/java/org/teavm/jso/impl/Imports.java
new file mode 100644
index 000000000..169344237
--- /dev/null
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/Imports.java
@@ -0,0 +1,27 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.jso.impl;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.CLASS)
+@Target(ElementType.METHOD)
+@interface Imports {
+    String[] value();
+}
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyAstEmitter.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyAstEmitter.java
index 022b6473c..497164c3e 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyAstEmitter.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyAstEmitter.java
@@ -32,12 +32,15 @@ class JSBodyAstEmitter implements JSBodyEmitter {
     private AstNode ast;
     private AstNode rootAst;
     private String[] parameterNames;
+    private JsBodyImportInfo[] imports;
 
-    JSBodyAstEmitter(boolean isStatic, AstNode ast, AstNode rootAst, String[] parameterNames) {
+    JSBodyAstEmitter(boolean isStatic, AstNode ast, AstNode rootAst, String[] parameterNames,
+            JsBodyImportInfo[] imports) {
         this.isStatic = isStatic;
         this.ast = ast;
         this.rootAst = rootAst;
         this.parameterNames = parameterNames;
+        this.imports = imports;
     }
 
     @Override
@@ -54,6 +57,10 @@ class JSBodyAstEmitter implements JSBodyEmitter {
             astWriter.declareNameEmitter(parameterNames[i],
                     prec -> context.writeExpr(context.getArgument(index), convert(prec)));
         }
+        for (var importInfo : imports) {
+            astWriter.declareNameEmitter(importInfo.alias,
+                    prec -> context.getWriter().appendFunction(context.importModule(importInfo.fromModule)));
+        }
         astWriter.hoist(rootAst);
         astWriter.print(ast, convert(context.getPrecedence()));
     }
@@ -148,9 +155,13 @@ class JSBodyAstEmitter implements JSBodyEmitter {
             int index = paramIndex++;
             astWriter.declareNameEmitter("this", prec -> writer.append(context.getParameterName(index)));
         }
-        for (int i = 0; i < parameterNames.length; ++i) {
+        for (var parameterName : parameterNames) {
             int index = paramIndex++;
-            astWriter.declareNameEmitter(parameterNames[i], prec -> writer.append(context.getParameterName(index)));
+            astWriter.declareNameEmitter(parameterName, prec -> writer.append(context.getParameterName(index)));
+        }
+        for (var importInfo : imports) {
+            astWriter.declareNameEmitter(importInfo.alias,
+                    prec -> writer.appendFunction(context.importModule(importInfo.fromModule)));
         }
         astWriter.hoist(rootAst);
         if (ast instanceof Block) {
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyBloatedEmitter.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyBloatedEmitter.java
index c2588e218..287bdc382 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyBloatedEmitter.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyBloatedEmitter.java
@@ -26,22 +26,45 @@ class JSBodyBloatedEmitter implements JSBodyEmitter {
     private MethodReference method;
     private String script;
     private String[] parameterNames;
+    private JsBodyImportInfo[] imports;
 
-    public JSBodyBloatedEmitter(boolean isStatic, MethodReference method, String script, String[] parameterNames) {
+    JSBodyBloatedEmitter(boolean isStatic, MethodReference method, String script, String[] parameterNames,
+            JsBodyImportInfo[] imports) {
         this.isStatic = isStatic;
         this.method = method;
         this.script = script;
         this.parameterNames = parameterNames;
+        this.imports = imports;
     }
 
     @Override
     public void emit(InjectorContext context) throws IOException {
-        emit(context.getWriter(), index -> context.writeExpr(context.getArgument(index)));
+        emit(context.getWriter(), new EmissionStrategy() {
+            @Override
+            public void emitArgument(int argument) {
+                context.writeExpr(context.getArgument(argument));
+            }
+
+            @Override
+            public void emitModule(String name) throws IOException {
+                context.getWriter().append(context.importModule(name));
+            }
+        });
     }
 
     @Override
     public void emit(GeneratorContext context, SourceWriter writer, MethodReference methodRef) throws IOException {
-        emit(writer, index -> writer.append(context.getParameterName(index + 1)));
+        emit(writer, new EmissionStrategy() {
+            @Override
+            public void emitArgument(int argument) throws IOException {
+                writer.append(context.getParameterName(argument + 1));
+            }
+
+            @Override
+            public void emitModule(String name) throws IOException {
+                writer.append(context.importModule(name));
+            }
+        });
     }
 
     private void emit(SourceWriter writer, EmissionStrategy strategy) throws IOException {
@@ -50,22 +73,43 @@ class JSBodyBloatedEmitter implements JSBodyEmitter {
         writer.append("if (!").appendMethodBody(method).append(".$native)").ws().append('{').indent().newLine();
         writer.appendMethodBody(method).append(".$native").ws().append('=').ws().append("function(");
         int count = method.parameterCount();
+
+        var first = true;
         for (int i = 0; i < count; ++i) {
-            if (i > 0) {
+            if (!first) {
                 writer.append(',').ws();
             }
+            first = false;
             writer.append('_').append(i);
         }
+        for (var i = 0; i < imports.length; ++i) {
+            if (!first) {
+                writer.append(',').ws();
+            }
+            first = false;
+            writer.append("_i").append(i);
+        }
         writer.append(')').ws().append('{').softNewLine().indent();
 
         writer.append("return (function(");
+
+        first = true;
         for (int i = 0; i < bodyParamCount; ++i) {
-            if (i > 0) {
+            if (!first) {
                 writer.append(',').ws();
             }
+            first = false;
             String name = parameterNames[i];
             writer.append(name);
         }
+        for (var importInfo : imports) {
+            if (!first) {
+                writer.append(',').ws();
+            }
+            first = false;
+            writer.append(importInfo.alias);
+        }
+
         writer.append(')').ws().append('{').softNewLine().indent();
         writer.append(script).softNewLine();
         writer.outdent().append("})");
@@ -73,12 +117,23 @@ class JSBodyBloatedEmitter implements JSBodyEmitter {
             writer.append(".call");
         }
         writer.append('(');
+
+        first = true;
         for (int i = 0; i < count; ++i) {
-            if (i > 0) {
+            if (!first) {
                 writer.append(',').ws();
             }
+            first = false;
             writer.append('_').append(i);
         }
+        for (var i = 0; i < imports.length; ++i) {
+            if (!first) {
+                writer.append(',').ws();
+            }
+            first = false;
+            writer.append("_i").append(i);
+        }
+
         writer.append(");").softNewLine();
         writer.outdent().append("};").softNewLine();
         writer.appendMethodBody(method).ws().append('=').ws().appendMethodBody(method).append(".$native;")
@@ -97,5 +152,7 @@ class JSBodyBloatedEmitter implements JSBodyEmitter {
 
     interface EmissionStrategy {
         void emitArgument(int argument) throws IOException;
+
+        void emitModule(String name) throws IOException;
     }
 }
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyRepository.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyRepository.java
index 24b803226..b93db9ba0 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyRepository.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSBodyRepository.java
@@ -22,10 +22,11 @@ import java.util.Set;
 import org.teavm.model.MethodReference;
 
 class JSBodyRepository {
-    public final Map<MethodReference, JSBodyEmitter> emitters = new HashMap<>();
-    public final Map<MethodReference, MethodReference> methodMap = new HashMap<>();
-    public final Set<MethodReference> processedMethods = new HashSet<>();
-    public final Set<MethodReference> inlineMethods = new HashSet<>();
-    public final Map<MethodReference, MethodReference> callbackCallees = new HashMap<>();
-    public final Map<MethodReference, Set<MethodReference>> callbackMethods = new HashMap<>();
+    final Map<MethodReference, JSBodyEmitter> emitters = new HashMap<>();
+    final Map<MethodReference, JsBodyImportInfo[]> imports = new HashMap<>();
+    final Map<MethodReference, MethodReference> methodMap = new HashMap<>();
+    final Set<MethodReference> processedMethods = new HashSet<>();
+    final Set<MethodReference> inlineMethods = new HashSet<>();
+    final Map<MethodReference, MethodReference> callbackCallees = new HashMap<>();
+    final Map<MethodReference, Set<MethodReference>> callbackMethods = new HashMap<>();
 }
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSClassProcessor.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSClassProcessor.java
index 397875824..f4107a802 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSClassProcessor.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSClassProcessor.java
@@ -780,10 +780,24 @@ class JSClassProcessor {
         }
         var body = ((FunctionNode) rootNode.getFirstChild()).getBody();
 
+        JsBodyImportInfo[] imports;
+        var importsValue = bodyAnnot.getValue("imports");
+        if (importsValue != null) {
+            var importsList = importsValue.getList();
+            imports = new JsBodyImportInfo[importsList.size()];
+            for (var i = 0; i < importsList.size(); ++i) {
+                var importAnnot = importsList.get(0).getAnnotation();
+                imports[i] = new JsBodyImportInfo(importAnnot.getValue("alias").getString(),
+                        importAnnot.getValue("fromModule").getString());
+            }
+        } else {
+            imports = new JsBodyImportInfo[0];
+        }
+
         repository.methodMap.put(methodToProcess.getReference(), proxyMethod);
         if (errorReporter.hasErrors()) {
             repository.emitters.put(proxyMethod, new JSBodyBloatedEmitter(isStatic, proxyMethod,
-                    script, parameterNames));
+                    script, parameterNames, imports));
         } else {
             var expr = JSBodyInlineUtil.isSuitableForInlining(methodToProcess.getReference(),
                     parameterNames, body);
@@ -793,7 +807,11 @@ class JSClassProcessor {
                 expr = body;
             }
             javaInvocationProcessor.process(location, expr);
-            repository.emitters.put(proxyMethod, new JSBodyAstEmitter(isStatic, expr, rootNode, parameterNames));
+            var emitter = new JSBodyAstEmitter(isStatic, expr, rootNode, parameterNames, imports);
+            repository.emitters.put(proxyMethod, emitter);
+        }
+        if (imports.length > 0) {
+            repository.imports.put(proxyMethod, imports);
         }
     }
 
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java b/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
index f291b02f8..aa5a02d93 100644
--- a/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JSOPlugin.java
@@ -78,5 +78,10 @@ public class JSOPlugin implements TeaVMPlugin {
                 wrapperGenerator);
 
         TeaVMPluginUtil.handleNatives(host, JS.class);
+
+        jsHost.addModuleImporterProvider(providerContext -> {
+            var imports = repository.imports.get(providerContext.getMethod());
+            return imports != null ? new JsBodyImportsContributor(imports) : null;
+        });
     }
 }
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportInfo.java b/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportInfo.java
new file mode 100644
index 000000000..3c4200b12
--- /dev/null
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportInfo.java
@@ -0,0 +1,26 @@
+/*
+ *  Copyright 2023 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.jso.impl;
+
+class JsBodyImportInfo {
+    final String alias;
+    final String fromModule;
+
+    JsBodyImportInfo(String alias, String fromModule) {
+        this.alias = alias;
+        this.fromModule = fromModule;
+    }
+}
diff --git a/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportsContributor.java b/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportsContributor.java
new file mode 100644
index 000000000..2f730b2eb
--- /dev/null
+++ b/jso/impl/src/main/java/org/teavm/jso/impl/JsBodyImportsContributor.java
@@ -0,0 +1,34 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.jso.impl;
+
+import org.teavm.backend.javascript.spi.ModuleImporter;
+import org.teavm.backend.javascript.spi.ModuleImporterContext;
+
+class JsBodyImportsContributor implements ModuleImporter {
+    private JsBodyImportInfo[] imports;
+
+    JsBodyImportsContributor(JsBodyImportInfo[] imports) {
+        this.imports = imports;
+    }
+
+    @Override
+    public void importModules(ModuleImporterContext context) {
+        for (var importInfo : imports) {
+            context.importModule(importInfo.fromModule);
+        }
+    }
+}
diff --git a/tests/src/test/java/org/teavm/jso/test/ImportModuleTest.java b/tests/src/test/java/org/teavm/jso/test/ImportModuleTest.java
new file mode 100644
index 000000000..dee379cfa
--- /dev/null
+++ b/tests/src/test/java/org/teavm/jso/test/ImportModuleTest.java
@@ -0,0 +1,52 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.jso.test;
+
+import static org.junit.Assert.assertEquals;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.teavm.jso.JSBody;
+import org.teavm.jso.JSBodyImport;
+import org.teavm.junit.AttachJavaScript;
+import org.teavm.junit.SkipJVM;
+import org.teavm.junit.TeaVMTestRunner;
+import org.teavm.junit.WholeClassCompilation;
+
+@RunWith(TeaVMTestRunner.class)
+@SkipJVM
+@WholeClassCompilation
+public class ImportModuleTest {
+    @Test
+    @AttachJavaScript({
+            "org/teavm/jso/test/amd.js",
+            "org/teavm/jso/test/amdModule.js"
+    })
+    public void amd() {
+        assertEquals(23, runTestFunction());
+    }
+
+    @Test
+    @AttachJavaScript("org/teavm/jso/test/commonjs.js")
+    public void commonjs() {
+        assertEquals(23, runTestFunction());
+    }
+
+    @JSBody(
+            script = "return testModule.foo();",
+            imports = @JSBodyImport(alias = "testModule", fromModule = "testModule.js")
+    )
+    private static native int runTestFunction();
+}
diff --git a/tests/src/test/resources/org/teavm/jso/test/amd.js b/tests/src/test/resources/org/teavm/jso/test/amd.js
new file mode 100644
index 000000000..d88a93b18
--- /dev/null
+++ b/tests/src/test/resources/org/teavm/jso/test/amd.js
@@ -0,0 +1,47 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+let main;
+const define = (function() {
+    const modules = new Map();
+    function def() {
+        let index = 0;
+        const moduleName = typeof arguments[index] === 'string' ? arguments[index++] : null;
+        const deps = arguments[index++];
+        const module = arguments[index++];
+
+        const exports = Object.create(null);
+        const args = [];
+        for (const dep of deps) {
+            if (dep === 'exports') {
+                args.push(exports);
+            } else {
+                args.push(modules[dep]);
+            }
+        }
+        let result = module.apply(this, args);
+        if (typeof result === 'undefined') {
+            result = exports;
+        }
+        if (moduleName !== null) {
+            modules[moduleName] = result;
+        } else {
+            main = result.main;
+        }
+    }
+    def.amd = {};
+    return def;
+})();
\ No newline at end of file
diff --git a/tests/src/test/resources/org/teavm/jso/test/amdModule.js b/tests/src/test/resources/org/teavm/jso/test/amdModule.js
new file mode 100644
index 000000000..f3558cc3d
--- /dev/null
+++ b/tests/src/test/resources/org/teavm/jso/test/amdModule.js
@@ -0,0 +1,23 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+define("testModule.js", [], () => {
+    return {
+        foo() {
+            return 23;
+        }
+    }
+});
\ No newline at end of file
diff --git a/tests/src/test/resources/org/teavm/jso/test/commonjs.js b/tests/src/test/resources/org/teavm/jso/test/commonjs.js
new file mode 100644
index 000000000..a0df8790e
--- /dev/null
+++ b/tests/src/test/resources/org/teavm/jso/test/commonjs.js
@@ -0,0 +1,36 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+function require(name) {
+    switch (name) {
+        case "testModule.js": {
+            return {
+                foo() {
+                    return 23;
+                }
+            }
+        }
+        default:
+            throw new Error("Unknown module: " + name);
+    }
+}
+
+let global = this;
+let exports = {};
+
+function main() {
+    exports.main.apply(this, arguments);
+}
\ No newline at end of file
diff --git a/tools/junit/src/main/java/org/teavm/junit/AttachJavaScript.java b/tools/junit/src/main/java/org/teavm/junit/AttachJavaScript.java
new file mode 100644
index 000000000..ce3db67fb
--- /dev/null
+++ b/tools/junit/src/main/java/org/teavm/junit/AttachJavaScript.java
@@ -0,0 +1,27 @@
+/*
+ *  Copyright 2023 konsoletyper.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.junit;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface AttachJavaScript {
+    String[] value();
+}
diff --git a/tools/junit/src/main/java/org/teavm/junit/BrowserRunStrategy.java b/tools/junit/src/main/java/org/teavm/junit/BrowserRunStrategy.java
index 723a7979b..8a66de29c 100644
--- a/tools/junit/src/main/java/org/teavm/junit/BrowserRunStrategy.java
+++ b/tools/junit/src/main/java/org/teavm/junit/BrowserRunStrategy.java
@@ -25,10 +25,11 @@ import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
-import java.io.OutputStream;
 import java.io.Reader;
 import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
+import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ConcurrentHashMap;
@@ -66,7 +67,7 @@ class BrowserRunStrategy implements TestRunStrategy {
     private ConcurrentMap<Integer, CallbackWrapper> awaitingRuns = new ConcurrentHashMap<>();
     private ObjectMapper objectMapper = new ObjectMapper();
 
-    public BrowserRunStrategy(File baseDir, String type, Function<String, Process> browserRunner) {
+    BrowserRunStrategy(File baseDir, String type, Function<String, Process> browserRunner) {
         this.baseDir = baseDir;
         this.type = type;
         this.browserRunner = browserRunner;
@@ -186,6 +187,16 @@ class BrowserRunStrategy implements TestRunStrategy {
         testNode.set("type", nf.textNode(type));
         testNode.set("name", nf.textNode(run.getFileName()));
         testNode.set("file", nf.textNode("tests/" + relPath));
+
+        var additionalJs = additionalJs(run);
+        if (additionalJs.length > 0) {
+            var additionalJsJson = nf.arrayNode();
+            for (var additionalFile : additionalJs) {
+                additionalJsJson.add("resources/" + additionalFile);
+            }
+            testNode.set("additionalFiles", additionalJsJson);
+        }
+
         if (run.getArgument() != null) {
             testNode.set("argument", nf.textNode(run.getArgument()));
         }
@@ -207,6 +218,27 @@ class BrowserRunStrategy implements TestRunStrategy {
         return !callbackWrapper.shouldRepeat;
     }
 
+    private String[] additionalJs(TestRun run) {
+        var result = new LinkedHashSet<String>();
+
+        var method = run.getMethod();
+        var attachAnnot = method.getAnnotation(AttachJavaScript.class);
+        if (attachAnnot != null) {
+            result.addAll(List.of(attachAnnot.value()));
+        }
+
+        var cls = method.getDeclaringClass();
+        while (cls != null) {
+            var classAttachAnnot = cls.getAnnotation(AttachJavaScript.class);
+            if (classAttachAnnot != null) {
+                result.addAll(List.of(attachAnnot.value()));
+            }
+            cls = cls.getSuperclass();
+        }
+
+        return result.toArray(new String[0]);
+    }
+
     class TestCodeServlet extends HttpServlet {
         private WebSocketServletFactory wsFactory;
         private Map<String, String> contentCache = new ConcurrentHashMap<>();
@@ -225,7 +257,7 @@ class BrowserRunStrategy implements TestRunStrategy {
         }
 
         @Override
-        protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
             String path = req.getRequestURI();
             if (path != null) {
                 if (!path.startsWith("/")) {
@@ -270,7 +302,20 @@ class BrowserRunStrategy implements TestRunStrategy {
                                 resp.setContentType("application/wasm");
                             }
                             try (FileInputStream input = new FileInputStream(file)) {
-                                copy(input, resp.getOutputStream());
+                                input.transferTo(resp.getOutputStream());
+                            }
+                            resp.getOutputStream().flush();
+                        }
+                    }
+                    if (path.startsWith("/resources/")) {
+                        var relPath = path.substring("/resources/".length());
+                        var classLoader = BrowserRunStrategy.class.getClassLoader();
+                        try (var input = classLoader.getResourceAsStream(relPath)) {
+                            if (input != null) {
+                                resp.setStatus(HttpServletResponse.SC_OK);
+                                input.transferTo(resp.getOutputStream());
+                            } else {
+                                resp.setStatus(HttpServletResponse.SC_NOT_FOUND);
                             }
                             resp.getOutputStream().flush();
                         }
@@ -309,17 +354,6 @@ class BrowserRunStrategy implements TestRunStrategy {
                 }
             });
         }
-
-        private void copy(InputStream input, OutputStream output) throws IOException {
-            byte[] buffer = new byte[2048];
-            while (true) {
-                int bytes = input.read(buffer);
-                if (bytes < 0) {
-                    break;
-                }
-                output.write(buffer, 0, bytes);
-            }
-        }
     }
 
     class TestCodeSocket extends WebSocketAdapter {
diff --git a/tools/junit/src/main/resources/test-server/frame.js b/tools/junit/src/main/resources/test-server/frame.js
index 4bcafb8c6..b35737426 100644
--- a/tools/junit/src/main/resources/test-server/frame.js
+++ b/tools/junit/src/main/resources/test-server/frame.js
@@ -20,7 +20,8 @@ window.addEventListener("message", event => {
     let request = event.data;
     switch (request.type) {
         case "JAVASCRIPT":
-            appendFiles([request.file], 0, () => {
+            const files = request.additionalFiles ? [...request.additionalFiles, request.file] : [request.file];
+            appendFiles(files, 0, () => {
                 launchTest(request.argument, response => {
                     event.source.postMessage(response, "*");
                 });