diff --git a/BUILD.gn b/BUILD.gn
index 233a0900e55..aaebd136ff1 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -110,6 +110,7 @@ group("dart2js") {
 group("dart2wasm_platform") {
   deps = [
     ":runtime_precompiled",
+    "utils/dart2wasm:compile_dart2wasm_js_compatibility_platform",
     "utils/dart2wasm:compile_dart2wasm_platform",
     "utils/dart2wasm:compile_dart2wasm_stringref_platform",
     "utils/dart2wasm:dart2wasm_snapshot",
diff --git a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
index fafdecbefe4..c483a5d8e7e 100644
--- a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
@@ -4500,7 +4500,7 @@ const MessageCode messageFastaUsageLong =
     Read the SDK platform from <file>, which should be in Dill/Kernel IR format
     and contain the Dart SDK.
 
-  --target=dart2js|dart2js_server|dart2wasm|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
+  --target=dart2js|dart2js_server|dart2wasm|dart2wasm_js_compatibility|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
     Specify the target configuration.
 
   --enable-asserts
diff --git a/pkg/dart2wasm/lib/target.dart b/pkg/dart2wasm/lib/target.dart
index 6fa2abb14d8..d4b726dcc52 100644
--- a/pkg/dart2wasm/lib/target.dart
+++ b/pkg/dart2wasm/lib/target.dart
@@ -34,11 +34,17 @@ import 'package:dart2wasm/ffi_native_transformer.dart' as wasmFfiNativeTrans;
 import 'package:dart2wasm/records.dart' show RecordShape;
 import 'package:dart2wasm/transformers.dart' as wasmTrans;
 
+enum Mode {
+  regular,
+  stringref,
+  jsCompatibility,
+}
+
 class WasmTarget extends Target {
-  WasmTarget({this.removeAsserts = true, this.useStringref = false});
+  WasmTarget({this.removeAsserts = true, this.mode = Mode.regular});
 
   bool removeAsserts;
-  bool useStringref;
+  Mode mode;
   Class? _growableList;
   Class? _immutableList;
   Class? _wasmDefaultMap;
@@ -59,7 +65,27 @@ class WasmTarget extends Target {
   Verification get verification => const WasmVerification();
 
   @override
-  String get name => useStringref ? 'wasm_stringref' : 'wasm';
+  String get name {
+    switch (mode) {
+      case Mode.regular:
+        return 'wasm';
+      case Mode.stringref:
+        return 'wasm_stringref';
+      case Mode.jsCompatibility:
+        return 'wasm_js_compatibility';
+    }
+  }
+
+  String get platformFile {
+    switch (mode) {
+      case Mode.regular:
+        return 'dart2wasm_platform.dill';
+      case Mode.stringref:
+        return 'dart2wasm_stringref_platform.dill';
+      case Mode.jsCompatibility:
+        return 'dart2wasm_js_compatibility_platform.dill';
+    }
+  }
 
   @override
   TargetFlags get flags => TargetFlags();
diff --git a/pkg/front_end/lib/src/compute_platform_binaries_location.dart b/pkg/front_end/lib/src/compute_platform_binaries_location.dart
index bba274a1b85..012c9f74d9c 100644
--- a/pkg/front_end/lib/src/compute_platform_binaries_location.dart
+++ b/pkg/front_end/lib/src/compute_platform_binaries_location.dart
@@ -86,6 +86,17 @@ String? computePlatformDillName(
           break;
       }
       break;
+    case 'wasm_js_compatibility':
+      switch (nnbdMode) {
+        case NnbdMode.Strong:
+          return 'dart2wasm_js_compatibility_outline.dill';
+        //TODO(johnniwinther): Support using the full dill.
+        //return 'dart2wasm_js_compatibility_platform.dill';
+        case NnbdMode.Weak:
+        case NnbdMode.Agnostic:
+          break;
+      }
+      break;
     default:
       break;
   }
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index 74a67d33dab..5b6b43f2bbf 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -2271,7 +2271,7 @@ FastaUsageLong:
         Read the SDK platform from <file>, which should be in Dill/Kernel IR format
         and contain the Dart SDK.
 
-      --target=dart2js|dart2js_server|dart2wasm|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
+      --target=dart2js|dart2js_server|dart2wasm|dart2wasm_js_compatibility|dart2wasm_stringref|dart_runner|dartdevc|flutter|flutter_runner|none|vm
         Specify the target configuration.
 
       --enable-asserts
diff --git a/pkg/front_end/test/spell_checking_list_common.txt b/pkg/front_end/test/spell_checking_list_common.txt
index a98aab153d9..3ff607d1441 100644
--- a/pkg/front_end/test/spell_checking_list_common.txt
+++ b/pkg/front_end/test/spell_checking_list_common.txt
@@ -738,6 +738,7 @@ dart
 dart2js
 dart2wasm
 dart2wasm_stringref
+dart2wasm_js_compatibility
 dartdevc
 data
 date
diff --git a/pkg/front_end/tool/_fasta/additional_targets.dart b/pkg/front_end/tool/_fasta/additional_targets.dart
index 6fbfda28d92..01a77853894 100644
--- a/pkg/front_end/tool/_fasta/additional_targets.dart
+++ b/pkg/front_end/tool/_fasta/additional_targets.dart
@@ -12,6 +12,8 @@ import 'package:dev_compiler/src/kernel/target.dart' show DevCompilerTarget;
 
 import 'package:dart2wasm/target.dart' show WasmTarget;
 
+import 'package:dart2wasm/target.dart' as wasm show Mode;
+
 import 'package:vm/target/install.dart' as vm_target_install
     show installAdditionalTargets;
 
@@ -25,6 +27,8 @@ void installAdditionalTargets() {
   targets["dartdevc"] = (TargetFlags flags) => new DevCompilerTarget(flags);
   targets["dart2wasm"] = (TargetFlags flags) => new WasmTarget();
   targets["dart2wasm_stringref"] =
-      (TargetFlags flags) => new WasmTarget(useStringref: true);
+      (TargetFlags flags) => new WasmTarget(mode: wasm.Mode.stringref);
+  targets["dart2wasm_js_compatibility"] =
+      (TargetFlags flags) => new WasmTarget(mode: wasm.Mode.jsCompatibility);
   vm_target_install.installAdditionalTargets();
 }
diff --git a/pkg/vm/test/common_test_utils.dart b/pkg/vm/test/common_test_utils.dart
index 8ebf5681808..5bd142209e5 100644
--- a/pkg/vm/test/common_test_utils.dart
+++ b/pkg/vm/test/common_test_utils.dart
@@ -37,9 +37,7 @@ Future<Component> compileTestCaseToKernelProgram(Uri sourceUri,
   Directory? tempDirectory;
   try {
     final platformFileName = (target is WasmTarget)
-        ? target.useStringref
-            ? 'dart2wasm_stringref_platform.dill'
-            : 'dart2wasm_platform.dill'
+        ? target.platformFile
         : 'vm_platform_strong.dill';
     final platformKernel =
         computePlatformBinariesLocation().resolve(platformFileName);
diff --git a/sdk/BUILD.gn b/sdk/BUILD.gn
index d84f0693dca..94b4fc3b70b 100644
--- a/sdk/BUILD.gn
+++ b/sdk/BUILD.gn
@@ -70,6 +70,8 @@ declare_args() {
 # ........dart2wasm_platform.dill (if not on ia32)
 # ........dart2wasm_stringref_outline.dill (if not on ia32)
 # ........dart2wasm_stringref_platform.dill (if not on ia32)
+# ........dart2wasm_js_compatibility_outline.dill (if not on ia32)
+# ........dart2wasm_js_compatibility_platform.dill (if not on ia32)
 # ........ddc_outline.dill
 # ........ddc_platform.dill
 # ........vm_platform_strong.dill
@@ -474,10 +476,13 @@ copy("copy_dart2wasm_platform") {
   deps = [
     ":copy_libraries",
     "../:dart2wasm_platform",
+    "../utils/dart2wasm:compile_dart2wasm_js_compatibility_platform",
     "../utils/dart2wasm:compile_dart2wasm_platform",
     "../utils/dart2wasm:compile_dart2wasm_stringref_platform",
   ]
   sources = [
+    "$root_out_dir/dart2wasm_js_compatibility_outline.dill",
+    "$root_out_dir/dart2wasm_js_compatibility_platform.dill",
     "$root_out_dir/dart2wasm_outline.dill",
     "$root_out_dir/dart2wasm_platform.dill",
     "$root_out_dir/dart2wasm_stringref_outline.dill",
diff --git a/sdk/bin/dart2wasm b/sdk/bin/dart2wasm
index 2f860fad891..3997e2da4e1 100755
--- a/sdk/bin/dart2wasm
+++ b/sdk/bin/dart2wasm
@@ -65,12 +65,15 @@ SDK_ARG="--dart-sdk=$SDK_DIR"
 
 # Point to built platform dill.
 PLATFORM="$BIN_DIR/dart2wasm_platform.dill"
-# Not the prettiest way to check for stringref, and it doesn't support changing
-# the default, but it will do for the experiment.
+# Not the prettiest way to check for a target, and it doesn't support changing
+# the default, but it will do for experiments.
 for arg in "$@"; do
   if [[ "$arg" == "--stringref" ]]; then
     PLATFORM="$BIN_DIR/dart2wasm_stringref_platform.dill"
   fi
+  if [[ "$arg" == "--js-compatibility" ]]; then
+    PLATFORM="$BIN_DIR/dart2wasm_js_compatibility_platform.dill"
+  fi
 done
 PLATFORM_ARG="--platform=$PLATFORM"
 
diff --git a/sdk/lib/libraries.json b/sdk/lib/libraries.json
index 171fdb5fa85..b25c195ad55 100644
--- a/sdk/lib/libraries.json
+++ b/sdk/lib/libraries.json
@@ -175,6 +175,34 @@
       }
     }
   },
+  "wasm_js_compatibility": {
+    "include": [
+      {
+        "target": "wasm_common"
+      }
+    ],
+    "libraries": {
+      "core": {
+        "uri": "core/core.dart",
+        "patches": [
+          "_internal/wasm/lib/core_patch.dart",
+          "_internal/vm_shared/lib/array_patch.dart",
+          "_internal/vm_shared/lib/bigint_patch.dart",
+          "_internal/vm_shared/lib/bool_patch.dart",
+          "_internal/vm_shared/lib/date_patch.dart",
+          "_internal/vm_shared/lib/integers_patch.dart",
+          "_internal/vm_shared/lib/map_patch.dart",
+          "_internal/vm_shared/lib/null_patch.dart",
+          "_internal/vm_shared/lib/string_buffer_patch.dart",
+          "_internal/wasm/lib/date_patch_patch.dart",
+          "_internal/wasm/lib/string_buffer_create.dart",
+          "_internal/wasm/lib/string_patch.dart",
+          "_internal/wasm/lib/sync_star_patch.dart",
+          "_internal/wasm/lib/weak_patch.dart"
+        ]
+      }
+    }
+  },
   "wasm_common": {
     "libraries": {
       "_http": {
diff --git a/sdk/lib/libraries.yaml b/sdk/lib/libraries.yaml
index be7edc7cdbf..003f98ccc8a 100644
--- a/sdk/lib/libraries.yaml
+++ b/sdk/lib/libraries.yaml
@@ -156,6 +156,28 @@ wasm_stringref:
       - _internal/wasm/lib/sync_star_patch.dart
       - _internal/wasm/lib/weak_patch.dart
 
+wasm_js_compatibility:
+  include:
+    - target: "wasm_common"
+  libraries:
+    core:
+      uri: core/core.dart
+      patches:
+      - _internal/wasm/lib/core_patch.dart
+      - _internal/vm_shared/lib/array_patch.dart
+      - _internal/vm_shared/lib/bigint_patch.dart
+      - _internal/vm_shared/lib/bool_patch.dart
+      - _internal/vm_shared/lib/date_patch.dart
+      - _internal/vm_shared/lib/integers_patch.dart
+      - _internal/vm_shared/lib/map_patch.dart
+      - _internal/vm_shared/lib/null_patch.dart
+      - _internal/vm_shared/lib/string_buffer_patch.dart
+      - _internal/wasm/lib/date_patch_patch.dart
+      - _internal/wasm/lib/string_buffer_create.dart
+      - _internal/wasm/lib/string_patch.dart
+      - _internal/wasm/lib/sync_star_patch.dart
+      - _internal/wasm/lib/weak_patch.dart
+
 wasm_common:
   libraries:
     _http:
diff --git a/tools/bots/test_matrix.json b/tools/bots/test_matrix.json
index 460077a3c30..b3c7d5db89b 100644
--- a/tools/bots/test_matrix.json
+++ b/tools/bots/test_matrix.json
@@ -126,6 +126,8 @@
       "out/ReleaseX64/dart2wasm_platform.dill",
       "out/ReleaseX64/dart2wasm_stringref_outline.dill",
       "out/ReleaseX64/dart2wasm_stringref_platform.dill",
+      "out/ReleaseX64/dart2wasm_js_compatibility_outline.dill",
+      "out/ReleaseX64/dart2wasm_js_compatibility_platform.dill",
       "out/ReleaseX64/wasm/",
       "pkg/",
       "runtime/tests/",
diff --git a/utils/dart2wasm/BUILD.gn b/utils/dart2wasm/BUILD.gn
index 8dde81e68c7..226b0e9579a 100644
--- a/utils/dart2wasm/BUILD.gn
+++ b/utils/dart2wasm/BUILD.gn
@@ -77,6 +77,24 @@ compile_platform("compile_dart2wasm_stringref_platform") {
   ]
 }
 
+compile_platform("compile_dart2wasm_js_compatibility_platform") {
+  single_root_scheme = "org-dartlang-sdk"
+  single_root_base = rebase_path("$sdk_root/")
+  libraries_specification_uri = "org-dartlang-sdk:///lib/libraries.json"
+
+  outputs = [
+    "$root_out_dir/dart2wasm_js_compatibility_platform.dill",
+    "$root_out_dir/dart2wasm_js_compatibility_outline.dill",
+  ]
+
+  args = [
+    "--target=dart2wasm_js_compatibility",
+    "--no-defines",
+    "dart:core",
+    "--nnbd-strong",
+  ]
+}
+
 wasm_module("ffi_native_test_wasm_module") {
   module_name = "ffi_native_test_module"
 }