Implement virtual module support in `Bun.plugin` (#6167)

* Add support for `build.module` in `Bun.plugin`

* Another test

* Update docs

* Update isBuiltinModule.cpp

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>
Co-authored-by: Dylan Conway <dylan.conway567@gmail.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/src/bun.js/bindings/ImportMetaObject.cpp b/src/bun.js/bindings/ImportMetaObject.cpp
index 4160102a5..340c3319b 100644
--- a/src/bun.js/bindings/ImportMetaObject.cpp
+++ b/src/bun.js/bindings/ImportMetaObject.cpp
@@ -64,6 +64,12 @@ static EncodedJSValue functionRequireResolve(JSC::JSGlobalObject* globalObject,
         JSC::JSValue moduleName = callFrame->argument(0);
 
         auto doIt = [&](const WTF::String& fromStr) -> JSC::EncodedJSValue {
+            if (auto* virtualModules = jsCast<Zig::GlobalObject*>(globalObject)->onLoadPlugins.virtualModules) {
+                if (virtualModules->contains(fromStr)) {
+                    return JSC::JSValue::encode(jsString(vm, fromStr));
+                }
+            }
+
             BunString from = Bun::toString(fromStr);
             auto result = Bun__resolveSyncWithSource(globalObject, JSC::JSValue::encode(moduleName), &from, false);
 
@@ -160,6 +166,14 @@ extern "C" EncodedJSValue functionImportMeta__resolveSync(JSC::JSGlobalObject* g
     JSC__JSValue from;
     bool isESM = true;
 
+    if (auto* virtualModules = jsCast<Zig::GlobalObject*>(globalObject)->onLoadPlugins.virtualModules) {
+        if (moduleName.isString()) {
+            if (virtualModules->contains(moduleName.toWTFString(globalObject))) {
+                return JSC::JSValue::encode(moduleName);
+            }
+        }
+    }
+
     if (callFrame->argumentCount() > 1) {
 
         if (callFrame->argumentCount() > 2) {
@@ -226,6 +240,7 @@ extern "C" EncodedJSValue functionImportMeta__resolveSyncPrivate(JSC::JSGlobalOb
 {
     JSC::VM& vm = globalObject->vm();
     auto scope = DECLARE_THROW_SCOPE(globalObject->vm());
+    auto* global = jsDynamicCast<Zig::GlobalObject*>(globalObject);
 
     JSC::JSValue moduleName = callFrame->argument(0);
     JSValue from = callFrame->argument(1);
@@ -239,8 +254,15 @@ extern "C" EncodedJSValue functionImportMeta__resolveSyncPrivate(JSC::JSGlobalOb
 
     RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::JSValue {}));
 
+    if (auto* virtualModules = global->onLoadPlugins.virtualModules) {
+        if (moduleName.isString()) {
+            if (virtualModules->contains(moduleName.toWTFString(globalObject))) {
+                return JSC::JSValue::encode(moduleName);
+            }
+        }
+    }
+
     if (!isESM) {
-        auto* global = jsDynamicCast<Zig::GlobalObject*>(globalObject);
         if (LIKELY(global)) {
             auto overrideHandler = global->m_nodeModuleOverriddenResolveFilename.get();
             if (UNLIKELY(overrideHandler)) {
@@ -289,6 +311,14 @@ JSC_DEFINE_HOST_FUNCTION(functionImportMeta__resolve,
 
         JSC__JSValue from;
 
+        if (auto* virtualModules = jsCast<Zig::GlobalObject*>(globalObject)->onLoadPlugins.virtualModules) {
+            if (moduleName.isString()) {
+                if (virtualModules->contains(moduleName.toWTFString(globalObject))) {
+                    return JSC::JSValue::encode(moduleName);
+                }
+            }
+        }
+
         if (callFrame->argumentCount() > 1 && callFrame->argument(1).isString()) {
             from = JSC::JSValue::encode(callFrame->argument(1));
         } else {