diff --git a/TODO b/TODO
index 1b02bfb..eb1563f 100644
--- a/TODO
+++ b/TODO
@@ -62,5 +62,5 @@ Optimization ideas:
 Test262o:   0/11262 errors, 463 excluded
 Test262o commit: 7da91bceb9ce7613f87db47ddd1292a2dda58b42 (es5-tests branch)
 
-Result: 58/79202 errors, 1610 excluded, 6738 skipped
+Result: 58/79349 errors, 1610 excluded, 6649 skipped
 Test262 commit: 27622d764767dcb3778784884022c2c7de5769b8
diff --git a/qjs.c b/qjs.c
index 2eaa9ee..a88e39a 100644
--- a/qjs.c
+++ b/qjs.c
@@ -465,7 +465,7 @@ int main(int argc, char **argv)
     }
 
     /* loader for ES6 modules */
-    JS_SetModuleLoaderFunc(rt, NULL, js_module_loader, NULL);
+    JS_SetModuleLoaderFunc2(rt, NULL, js_module_loader, js_module_check_attributes, NULL);
 
     if (dump_unhandled_promise_rejection) {
         JS_SetHostPromiseRejectionTracker(rt, js_std_promise_rejection_tracker,
diff --git a/qjsc.c b/qjsc.c
index f9e1928..4c6b28b 100644
--- a/qjsc.c
+++ b/qjsc.c
@@ -788,7 +788,7 @@ int main(int argc, char **argv)
 
         /* add the module loader if necessary */
         if (feature_bitmap & (1 << FE_MODULE_LOADER)) {
-            fprintf(fo, "  JS_SetModuleLoaderFunc(rt, NULL, js_module_loader, NULL);\n");
+            fprintf(fo, "  JS_SetModuleLoaderFunc2(rt, NULL, js_module_loader, js_module_check_attributes, NULL);\n");
         }
 
         fprintf(fo,
diff --git a/quickjs-libc.c b/quickjs-libc.c
index 03ce012..ca8e359 100644
--- a/quickjs-libc.c
+++ b/quickjs-libc.c
@@ -591,8 +591,72 @@ int js_module_set_import_meta(JSContext *ctx, JSValueConst func_val,
     return 0;
 }
 
+static int json_module_init(JSContext *ctx, JSModuleDef *m)
+{
+    JSValue val;
+    val = JS_GetModulePrivateValue(ctx, m);
+    JS_SetModuleExport(ctx, m, "default", val);
+    return 0;
+}
+
+/* in order to conform with the specification, only the keys should be
+   tested and not the associated values. */
+int js_module_check_attributes(JSContext *ctx, void *opaque,
+                               JSValueConst attributes)
+{
+    JSPropertyEnum *tab;
+    uint32_t i, len;
+    int ret;
+    const char *cstr;
+    size_t cstr_len;
+    
+    if (JS_GetOwnPropertyNames(ctx, &tab, &len, attributes, JS_GPN_ENUM_ONLY | JS_GPN_STRING_MASK))
+        return -1;
+    ret = 0;
+    for(i = 0; i < len; i++) {
+        cstr = JS_AtomToCStringLen(ctx, &cstr_len, tab[i].atom);
+        if (!cstr) {
+            ret = -1;
+            break;
+        }
+        if (!(cstr_len == 4 && !memcmp(cstr, "type", cstr_len))) {
+            JS_ThrowTypeError(ctx, "import attribute '%s' is not supported", cstr);
+            ret = -1;
+        }
+        JS_FreeCString(ctx, cstr);
+        if (ret)
+            break;
+    }
+    JS_FreePropertyEnum(ctx, tab, len);
+    return ret;
+}
+
+/* return TRUE if the attributes indicate a JSON module */
+JS_BOOL js_module_test_json(JSContext *ctx, JSValueConst attributes)
+{
+    JSValue str;
+    const char *cstr;
+    size_t len;
+    BOOL res;
+
+    if (JS_IsUndefined(attributes))
+        return FALSE;
+    str = JS_GetPropertyStr(ctx, attributes, "type");
+    if (!JS_IsString(str))
+        return FALSE;
+    cstr = JS_ToCStringLen(ctx, &len, str);
+    JS_FreeValue(ctx, str);
+    if (!cstr)
+        return FALSE;
+    /* XXX: raise an error if unknown type ? */
+    res = (len == 4 && !memcmp(cstr, "json", len));
+    JS_FreeCString(ctx, cstr);
+    return res;
+}
+
 JSModuleDef *js_module_loader(JSContext *ctx,
-                              const char *module_name, void *opaque)
+                              const char *module_name, void *opaque,
+                              JSValueConst attributes)
 {
     JSModuleDef *m;
 
@@ -601,7 +665,6 @@ JSModuleDef *js_module_loader(JSContext *ctx,
     } else {
         size_t buf_len;
         uint8_t *buf;
-        JSValue func_val;
 
         buf = js_load_file(ctx, &buf_len, module_name);
         if (!buf) {
@@ -609,18 +672,37 @@ JSModuleDef *js_module_loader(JSContext *ctx,
                                    module_name);
             return NULL;
         }
-
-        /* compile the module */
-        func_val = JS_Eval(ctx, (char *)buf, buf_len, module_name,
-                           JS_EVAL_TYPE_MODULE | JS_EVAL_FLAG_COMPILE_ONLY);
-        js_free(ctx, buf);
-        if (JS_IsException(func_val))
-            return NULL;
-        /* XXX: could propagate the exception */
-        js_module_set_import_meta(ctx, func_val, TRUE, FALSE);
-        /* the module is already referenced, so we must free it */
-        m = JS_VALUE_GET_PTR(func_val);
-        JS_FreeValue(ctx, func_val);
+        
+        if (has_suffix(module_name, ".json") ||
+            js_module_test_json(ctx, attributes)) {
+            /* compile as JSON */
+            JSValue val;
+            val = JS_ParseJSON(ctx, (char *)buf, buf_len, module_name);
+            js_free(ctx, buf);
+            if (JS_IsException(val))
+                return NULL;
+            m = JS_NewCModule(ctx, module_name, json_module_init);
+            if (!m) {
+                JS_FreeValue(ctx, val);
+                return NULL;
+            }
+            /* only export the "default" symbol which will contain the JSON object */
+            JS_AddModuleExport(ctx, m, "default");
+            JS_SetModulePrivateValue(ctx, m, val);
+        } else {
+            JSValue func_val;
+            /* compile the module */
+            func_val = JS_Eval(ctx, (char *)buf, buf_len, module_name,
+                               JS_EVAL_TYPE_MODULE | JS_EVAL_FLAG_COMPILE_ONLY);
+            js_free(ctx, buf);
+            if (JS_IsException(func_val))
+                return NULL;
+            /* XXX: could propagate the exception */
+            js_module_set_import_meta(ctx, func_val, TRUE, FALSE);
+            /* the module is already referenced, so we must free it */
+            m = JS_VALUE_GET_PTR(func_val);
+            JS_FreeValue(ctx, func_val);
+        }
     }
     return m;
 }
@@ -3478,7 +3560,7 @@ static void *worker_func(void *opaque)
     JS_SetStripInfo(rt, args->strip_flags);
     js_std_init_handlers(rt);
 
-    JS_SetModuleLoaderFunc(rt, NULL, js_module_loader, NULL);
+    JS_SetModuleLoaderFunc2(rt, NULL, js_module_loader, js_module_check_attributes, NULL);
 
     /* set the pipe to communicate with the parent */
     ts = JS_GetRuntimeOpaque(rt);
diff --git a/quickjs-libc.h b/quickjs-libc.h
index 850484f..f24e161 100644
--- a/quickjs-libc.h
+++ b/quickjs-libc.h
@@ -44,8 +44,11 @@ void js_std_dump_error(JSContext *ctx);
 uint8_t *js_load_file(JSContext *ctx, size_t *pbuf_len, const char *filename);
 int js_module_set_import_meta(JSContext *ctx, JSValueConst func_val,
                               JS_BOOL use_realpath, JS_BOOL is_main);
+JS_BOOL js_module_test_json(JSContext *ctx, JSValueConst attributes);
+int js_module_check_attributes(JSContext *ctx, void *opaque, JSValueConst attributes);
 JSModuleDef *js_module_loader(JSContext *ctx,
-                              const char *module_name, void *opaque);
+                              const char *module_name, void *opaque,
+                              JSValueConst attributes);
 void js_std_eval_binary(JSContext *ctx, const uint8_t *buf, size_t buf_len,
                         int flags);
 void js_std_promise_rejection_tracker(JSContext *ctx, JSValueConst promise,
diff --git a/quickjs-opcode.h b/quickjs-opcode.h
index e721e17..814a7cb 100644
--- a/quickjs-opcode.h
+++ b/quickjs-opcode.h
@@ -121,7 +121,7 @@ DEF(     apply_eval, 3, 2, 1, u16) /* func array -> ret_eval */
 DEF(         regexp, 1, 2, 1, none) /* create a RegExp object from the pattern and a
                                        bytecode string */
 DEF(      get_super, 1, 1, 1, none)
-DEF(         import, 1, 1, 1, none) /* dynamic module import */
+DEF(         import, 1, 2, 1, none) /* dynamic module import */
 
 DEF(      check_var, 5, 0, 1, atom) /* check if a variable exists */
 DEF(  get_var_undef, 5, 0, 1, atom) /* push undefined if the variable does not exist */
diff --git a/quickjs.c b/quickjs.c
index eb94306..475232c 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -280,7 +280,12 @@ struct JSRuntime {
     struct list_head job_list; /* list of JSJobEntry.link */
 
     JSModuleNormalizeFunc *module_normalize_func;
-    JSModuleLoaderFunc *module_loader_func;
+    BOOL module_loader_has_attr;
+    union {
+        JSModuleLoaderFunc *module_loader_func;
+        JSModuleLoaderFunc2 *module_loader_func2;
+    } u;
+    JSModuleCheckSupportedImportAttributes *module_check_attrs;
     void *module_loader_opaque;
     /* timestamp for internal use in module evaluation */
     int64_t module_async_evaluation_next_timestamp;
@@ -756,6 +761,7 @@ typedef struct {
 typedef struct JSReqModuleEntry {
     JSAtom module_name;
     JSModuleDef *module; /* used using resolution */
+    JSValue attributes; /* JS_UNDEFINED or an object contains the attributes as key/value */
 } JSReqModuleEntry;
 
 typedef enum JSExportTypeEnum {
@@ -844,6 +850,7 @@ struct JSModuleDef {
     BOOL eval_has_exception : 8;
     JSValue eval_exception;
     JSValue meta_obj; /* for import.meta */
+    JSValue private_value; /* private value for C modules */
 };
 
 typedef struct JSJobEntry {
@@ -1217,7 +1224,7 @@ static void js_free_module_def(JSContext *ctx, JSModuleDef *m);
 static void js_mark_module_def(JSRuntime *rt, JSModuleDef *m,
                                JS_MarkFunc *mark_func);
 static JSValue js_import_meta(JSContext *ctx);
-static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier);
+static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier, JSValueConst options);
 static void free_var_ref(JSRuntime *rt, JSVarRef *var_ref);
 static JSValue js_new_promise_capability(JSContext *ctx,
                                          JSValue *resolving_funcs,
@@ -17383,10 +17390,12 @@ static JSValue JS_CallInternal(JSContext *caller_ctx, JSValueConst func_obj,
             {
                 JSValue val;
                 sf->cur_pc = pc;
-                val = js_dynamic_import(ctx, sp[-1]);
+                val = js_dynamic_import(ctx, sp[-2], sp[-1]);
                 if (JS_IsException(val))
                     goto exception;
+                JS_FreeValue(ctx, sp[-2]);
                 JS_FreeValue(ctx, sp[-1]);
+                sp--;
                 sp[-1] = val;
             }
             BREAK;
@@ -25538,6 +25547,23 @@ static __exception int js_parse_postfix_expr(JSParseState *s, int parse_flags)
                 return js_parse_error(s, "invalid use of 'import()'");
             if (js_parse_assign_expr(s))
                 return -1;
+            if (s->token.val == ',') {
+                if (next_token(s))
+                    return -1;
+                if (s->token.val != ')') {
+                    if (js_parse_assign_expr(s))
+                        return -1;
+                    /* accept a trailing comma */
+                    if (s->token.val == ',') {
+                        if (next_token(s))
+                            return -1;
+                    }
+                } else {
+                    emit_op(s, OP_undefined);
+                }
+            } else {
+                emit_op(s, OP_undefined);
+            }
             if (js_parse_expect(s, ')'))
                 return -1;
             emit_op(s, OP_import);
@@ -28115,6 +28141,7 @@ static JSModuleDef *js_new_module_def(JSContext *ctx, JSAtom name)
     m->promise = JS_UNDEFINED;
     m->resolving_funcs[0] = JS_UNDEFINED;
     m->resolving_funcs[1] = JS_UNDEFINED;
+    m->private_value = JS_UNDEFINED;
     list_add_tail(&m->link, &ctx->loaded_modules);
     return m;
 }
@@ -28124,6 +28151,11 @@ static void js_mark_module_def(JSRuntime *rt, JSModuleDef *m,
 {
     int i;
 
+    for(i = 0; i < m->req_module_entries_count; i++) {
+        JSReqModuleEntry *rme = &m->req_module_entries[i];
+        JS_MarkValue(rt, rme->attributes, mark_func);
+    }
+    
     for(i = 0; i < m->export_entries_count; i++) {
         JSExportEntry *me = &m->export_entries[i];
         if (me->export_type == JS_EXPORT_TYPE_LOCAL &&
@@ -28139,6 +28171,7 @@ static void js_mark_module_def(JSRuntime *rt, JSModuleDef *m,
     JS_MarkValue(rt, m->promise, mark_func);
     JS_MarkValue(rt, m->resolving_funcs[0], mark_func);
     JS_MarkValue(rt, m->resolving_funcs[1], mark_func);
+    JS_MarkValue(rt, m->private_value, mark_func);
 }
 
 static void js_free_module_def(JSContext *ctx, JSModuleDef *m)
@@ -28150,6 +28183,7 @@ static void js_free_module_def(JSContext *ctx, JSModuleDef *m)
     for(i = 0; i < m->req_module_entries_count; i++) {
         JSReqModuleEntry *rme = &m->req_module_entries[i];
         JS_FreeAtom(ctx, rme->module_name);
+        JS_FreeValue(ctx, rme->attributes);
     }
     js_free(ctx, m->req_module_entries);
 
@@ -28178,6 +28212,7 @@ static void js_free_module_def(JSContext *ctx, JSModuleDef *m)
     JS_FreeValue(ctx, m->promise);
     JS_FreeValue(ctx, m->resolving_funcs[0]);
     JS_FreeValue(ctx, m->resolving_funcs[1]);
+    JS_FreeValue(ctx, m->private_value);
     list_del(&m->link);
     js_free(ctx, m);
 }
@@ -28186,14 +28221,6 @@ static int add_req_module_entry(JSContext *ctx, JSModuleDef *m,
                                 JSAtom module_name)
 {
     JSReqModuleEntry *rme;
-    int i;
-
-    /* no need to add the module request if it is already present */
-    for(i = 0; i < m->req_module_entries_count; i++) {
-        rme = &m->req_module_entries[i];
-        if (rme->module_name == module_name)
-            return i;
-    }
 
     if (js_resize_array(ctx, (void **)&m->req_module_entries,
                         sizeof(JSReqModuleEntry),
@@ -28203,7 +28230,8 @@ static int add_req_module_entry(JSContext *ctx, JSModuleDef *m,
     rme = &m->req_module_entries[m->req_module_entries_count++];
     rme->module_name = JS_DupAtom(ctx, module_name);
     rme->module = NULL;
-    return i;
+    rme->attributes = JS_UNDEFINED;
+    return m->req_module_entries_count - 1;
 }
 
 static JSExportEntry *find_export_entry(JSContext *ctx, JSModuleDef *m,
@@ -28322,12 +28350,38 @@ int JS_SetModuleExport(JSContext *ctx, JSModuleDef *m, const char *export_name,
     return -1;
 }
 
+int JS_SetModulePrivateValue(JSContext *ctx, JSModuleDef *m, JSValue val)
+{
+    set_value(ctx, &m->private_value, val);
+    return 0;
+}
+
+JSValue JS_GetModulePrivateValue(JSContext *ctx, JSModuleDef *m)
+{
+    return JS_DupValue(ctx, m->private_value);
+}
+
 void JS_SetModuleLoaderFunc(JSRuntime *rt,
                             JSModuleNormalizeFunc *module_normalize,
                             JSModuleLoaderFunc *module_loader, void *opaque)
 {
     rt->module_normalize_func = module_normalize;
-    rt->module_loader_func = module_loader;
+    rt->module_loader_has_attr = FALSE;
+    rt->u.module_loader_func = module_loader;
+    rt->module_check_attrs = NULL;
+    rt->module_loader_opaque = opaque;
+}
+
+void JS_SetModuleLoaderFunc2(JSRuntime *rt,
+                             JSModuleNormalizeFunc *module_normalize,
+                             JSModuleLoaderFunc2 *module_loader,
+                             JSModuleCheckSupportedImportAttributes *module_check_attrs,
+                             void *opaque)
+{
+    rt->module_normalize_func = module_normalize;
+    rt->module_loader_has_attr = TRUE;
+    rt->u.module_loader_func2 = module_loader;
+    rt->module_check_attrs = module_check_attrs;
     rt->module_loader_opaque = opaque;
 }
 
@@ -28408,7 +28462,8 @@ static JSModuleDef *js_find_loaded_module(JSContext *ctx, JSAtom name)
 /* return NULL in case of exception (e.g. module could not be loaded) */
 static JSModuleDef *js_host_resolve_imported_module(JSContext *ctx,
                                                     const char *base_cname,
-                                                    const char *cname1)
+                                                    const char *cname1,
+                                                    JSValueConst attributes)
 {
     JSRuntime *rt = ctx->rt;
     JSModuleDef *m;
@@ -28441,22 +28496,26 @@ static JSModuleDef *js_host_resolve_imported_module(JSContext *ctx,
     JS_FreeAtom(ctx, module_name);
 
     /* load the module */
-    if (!rt->module_loader_func) {
+    if (!rt->u.module_loader_func) {
         /* XXX: use a syntax error ? */
         JS_ThrowReferenceError(ctx, "could not load module '%s'",
                                cname);
         js_free(ctx, cname);
         return NULL;
     }
-
-    m = rt->module_loader_func(ctx, cname, rt->module_loader_opaque);
+    if (rt->module_loader_has_attr) {
+        m = rt->u.module_loader_func2(ctx, cname, rt->module_loader_opaque, attributes);
+    } else {
+        m = rt->u.module_loader_func(ctx, cname, rt->module_loader_opaque);
+    }
     js_free(ctx, cname);
     return m;
 }
 
 static JSModuleDef *js_host_resolve_imported_module_atom(JSContext *ctx,
-                                                    JSAtom base_module_name,
-                                                    JSAtom module_name1)
+                                                         JSAtom base_module_name,
+                                                         JSAtom module_name1,
+                                                         JSValueConst attributes)
 {
     const char *base_cname, *cname;
     JSModuleDef *m;
@@ -28469,7 +28528,7 @@ static JSModuleDef *js_host_resolve_imported_module_atom(JSContext *ctx,
         JS_FreeCString(ctx, base_cname);
         return NULL;
     }
-    m = js_host_resolve_imported_module(ctx, base_cname, cname);
+    m = js_host_resolve_imported_module(ctx, base_cname, cname, attributes);
     JS_FreeCString(ctx, base_cname);
     JS_FreeCString(ctx, cname);
     return m;
@@ -28931,7 +28990,8 @@ static int js_resolve_module(JSContext *ctx, JSModuleDef *m)
     for(i = 0; i < m->req_module_entries_count; i++) {
         JSReqModuleEntry *rme = &m->req_module_entries[i];
         m1 = js_host_resolve_imported_module_atom(ctx, m->module_name,
-                                                  rme->module_name);
+                                                  rme->module_name,
+                                                  rme->attributes);
         if (!m1)
             return -1;
         rme->module = m1;
@@ -29408,14 +29468,15 @@ static JSValue js_load_module_fulfilled(JSContext *ctx, JSValueConst this_val,
 
 static void JS_LoadModuleInternal(JSContext *ctx, const char *basename,
                                   const char *filename,
-                                  JSValueConst *resolving_funcs)
+                                  JSValueConst *resolving_funcs,
+                                  JSValueConst attributes)
 {
     JSValue evaluate_promise;
     JSModuleDef *m;
     JSValue ret, err, func_obj, evaluate_resolving_funcs[2];
     JSValueConst func_data[3];
 
-    m = js_host_resolve_imported_module(ctx, basename, filename);
+    m = js_host_resolve_imported_module(ctx, basename, filename, attributes);
     if (!m)
         goto fail;
 
@@ -29462,7 +29523,7 @@ JSValue JS_LoadModule(JSContext *ctx, const char *basename,
     if (JS_IsException(promise))
         return JS_EXCEPTION;
     JS_LoadModuleInternal(ctx, basename, filename,
-                          (JSValueConst *)resolving_funcs);
+                          (JSValueConst *)resolving_funcs, JS_UNDEFINED);
     JS_FreeValue(ctx, resolving_funcs[0]);
     JS_FreeValue(ctx, resolving_funcs[1]);
     return promise;
@@ -29474,6 +29535,7 @@ static JSValue js_dynamic_import_job(JSContext *ctx,
     JSValueConst *resolving_funcs = argv;
     JSValueConst basename_val = argv[2];
     JSValueConst specifier = argv[3];
+    JSValueConst attributes = argv[4];
     const char *basename = NULL, *filename;
     JSValue ret, err;
 
@@ -29490,7 +29552,7 @@ static JSValue js_dynamic_import_job(JSContext *ctx,
         goto exception;
 
     JS_LoadModuleInternal(ctx, basename, filename,
-                          resolving_funcs);
+                          resolving_funcs, attributes);
     JS_FreeCString(ctx, filename);
     JS_FreeCString(ctx, basename);
     return JS_UNDEFINED;
@@ -29504,11 +29566,12 @@ static JSValue js_dynamic_import_job(JSContext *ctx,
     return JS_UNDEFINED;
 }
 
-static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier)
+static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier, JSValueConst options)
 {
     JSAtom basename;
-    JSValue promise, resolving_funcs[2], basename_val;
-    JSValueConst args[4];
+    JSValue promise, resolving_funcs[2], basename_val, err, ret;
+    JSValue specifier_str = JS_UNDEFINED, attributes = JS_UNDEFINED, attributes_obj = JS_UNDEFINED;
+    JSValueConst args[5];
 
     basename = JS_GetScriptOrModuleName(ctx, 0);
     if (basename == JS_ATOM_NULL)
@@ -29525,19 +29588,82 @@ static JSValue js_dynamic_import(JSContext *ctx, JSValueConst specifier)
         return promise;
     }
 
+    /* the string conversion must occur here */
+    specifier_str = JS_ToString(ctx, specifier);
+    if (JS_IsException(specifier_str))
+        goto exception;
+    
+    if (!JS_IsUndefined(options)) {
+        if (!JS_IsObject(options)) {
+            JS_ThrowTypeError(ctx, "options must be an object");
+            goto exception;
+        }
+        attributes_obj = JS_GetProperty(ctx, options, JS_ATOM_with);
+        if (JS_IsException(attributes_obj))
+            goto exception;
+        if (!JS_IsUndefined(attributes_obj)) {
+            JSPropertyEnum *atoms;
+            uint32_t atoms_len, i;
+            JSValue val;
+            
+            if (!JS_IsObject(attributes_obj)) {
+                JS_ThrowTypeError(ctx, "options.with must be an object");
+                goto exception;
+            }
+            attributes = JS_NewObjectProto(ctx, JS_NULL);
+            if (JS_GetOwnPropertyNamesInternal(ctx, &atoms, &atoms_len, JS_VALUE_GET_OBJ(attributes_obj),
+                                               JS_GPN_STRING_MASK | JS_GPN_ENUM_ONLY)) {
+                goto exception;
+            }
+            for(i = 0; i < atoms_len; i++) {
+                val = JS_GetProperty(ctx, attributes_obj, atoms[i].atom);
+                if (JS_IsException(val))
+                    goto exception1;
+                if (!JS_IsString(val)) {
+                    JS_FreeValue(ctx, val);
+                    JS_ThrowTypeError(ctx, "module attribute values must be strings");
+                    goto exception1;
+                }
+                if (JS_DefinePropertyValue(ctx, attributes,  atoms[i].atom, val,
+                                           JS_PROP_C_W_E) < 0) {
+                exception1:
+                    JS_FreePropertyEnum(ctx, atoms, atoms_len);
+                    goto exception;
+                }
+            }
+            JS_FreePropertyEnum(ctx, atoms, atoms_len);
+            if (ctx->rt->module_check_attrs &&
+                ctx->rt->module_check_attrs(ctx, ctx->rt->module_loader_opaque, attributes) < 0) {
+                goto exception;
+            }
+            JS_FreeValue(ctx, attributes_obj);
+        }
+    }
+
     args[0] = resolving_funcs[0];
     args[1] = resolving_funcs[1];
     args[2] = basename_val;
-    args[3] = specifier;
-
+    args[3] = specifier_str;
+    args[4] = attributes;
+    
     /* cannot run JS_LoadModuleInternal synchronously because it would
        cause an unexpected recursion in js_evaluate_module() */
-    JS_EnqueueJob(ctx, js_dynamic_import_job, 4, args);
-
+    JS_EnqueueJob(ctx, js_dynamic_import_job, 5, args);
+ done:
     JS_FreeValue(ctx, basename_val);
     JS_FreeValue(ctx, resolving_funcs[0]);
     JS_FreeValue(ctx, resolving_funcs[1]);
+    JS_FreeValue(ctx, specifier_str);
+    JS_FreeValue(ctx, attributes);
     return promise;
+ exception:
+    JS_FreeValue(ctx, attributes_obj);
+    err = JS_GetException(ctx);
+    ret = JS_Call(ctx, resolving_funcs[1], JS_UNDEFINED,
+                   1, (JSValueConst *)&err);
+    JS_FreeValue(ctx, ret);
+    JS_FreeValue(ctx, err);
+    goto done;
 }
 
 static void js_set_module_evaluated(JSContext *ctx, JSModuleDef *m)
@@ -29933,27 +30059,109 @@ static JSValue js_evaluate_module(JSContext *ctx, JSModuleDef *m)
     return JS_DupValue(ctx, m->promise);
 }
 
-static __exception JSAtom js_parse_from_clause(JSParseState *s)
+static __exception int js_parse_with_clause(JSParseState *s, JSReqModuleEntry *rme)
+{
+    JSContext *ctx = s->ctx;
+    JSAtom key;
+    int ret;
+    const uint8_t *key_token_ptr;
+    
+    if (next_token(s))
+        return -1;
+    if (js_parse_expect(s, '{'))
+        return -1;
+    while (s->token.val != '}') {
+        key_token_ptr = s->token.ptr;
+        if (s->token.val == TOK_STRING) {
+            key = JS_ValueToAtom(ctx, s->token.u.str.str);
+            if (key == JS_ATOM_NULL)
+                return -1;
+        } else {
+            if (!token_is_ident(s->token.val)) {
+                js_parse_error(s, "identifier expected");
+                return -1;
+            }
+            key = JS_DupAtom(ctx, s->token.u.ident.atom);
+        }
+        if (next_token(s))
+            return -1;
+        if (js_parse_expect(s, ':')) {
+            JS_FreeAtom(ctx, key);
+            return -1;
+        }
+        if (s->token.val != TOK_STRING) {
+            js_parse_error_pos(s, key_token_ptr, "string expected");
+            return -1;
+        }
+        if (JS_IsUndefined(rme->attributes)) {
+            JSValue attributes = JS_NewObjectProto(ctx, JS_NULL);
+            if (JS_IsException(attributes)) {
+                JS_FreeAtom(ctx, key);
+                return -1;
+            }
+            rme->attributes = attributes;
+        }
+        ret = JS_HasProperty(ctx, rme->attributes, key);
+        if (ret != 0) {
+            JS_FreeAtom(ctx, key);
+            if (ret < 0)
+                return -1;
+            else
+                return js_parse_error(s, "duplicate with key");
+        }
+        ret = JS_DefinePropertyValue(ctx, rme->attributes, key,
+                                     JS_DupValue(ctx, s->token.u.str.str), JS_PROP_C_W_E);
+        JS_FreeAtom(ctx, key);
+        if (ret < 0)
+            return -1;
+        if (next_token(s))
+            return -1;
+        if (s->token.val != ',')
+            break;
+        if (next_token(s))
+            return -1;
+    }
+    if (!JS_IsUndefined(rme->attributes) &&
+        ctx->rt->module_check_attrs &&
+        ctx->rt->module_check_attrs(ctx, ctx->rt->module_loader_opaque, rme->attributes) < 0) {
+        return -1;
+    }
+    return js_parse_expect(s, '}');
+}
+
+/* return the module index in m->req_module_entries[] or < 0 if error */
+static __exception int js_parse_from_clause(JSParseState *s, JSModuleDef *m)
 {
     JSAtom module_name;
+    int idx;
+
     if (!token_is_pseudo_keyword(s, JS_ATOM_from)) {
         js_parse_error(s, "from clause expected");
-        return JS_ATOM_NULL;
+        return -1;
     }
     if (next_token(s))
-        return JS_ATOM_NULL;
+        return -1;
     if (s->token.val != TOK_STRING) {
         js_parse_error(s, "string expected");
-        return JS_ATOM_NULL;
+        return -1;
     }
     module_name = JS_ValueToAtom(s->ctx, s->token.u.str.str);
     if (module_name == JS_ATOM_NULL)
-        return JS_ATOM_NULL;
+        return -1;
     if (next_token(s)) {
         JS_FreeAtom(s->ctx, module_name);
-        return JS_ATOM_NULL;
+        return -1;
     }
-    return module_name;
+
+    idx = add_req_module_entry(s->ctx, m, module_name);
+    JS_FreeAtom(s->ctx, module_name);
+    if (idx < 0)
+        return -1;
+    if (s->token.val == TOK_WITH) {
+        if (js_parse_with_clause(s, &m->req_module_entries[idx]))
+            return -1;
+    }
+    return idx;
 }
 
 static __exception int js_parse_export(JSParseState *s)
@@ -29962,7 +30170,6 @@ static __exception int js_parse_export(JSParseState *s)
     JSModuleDef *m = s->cur_func->module;
     JSAtom local_name, export_name;
     int first_export, idx, i, tok;
-    JSAtom module_name;
     JSExportEntry *me;
 
     if (next_token(s))
@@ -30037,11 +30244,7 @@ static __exception int js_parse_export(JSParseState *s)
         if (js_parse_expect(s, '}'))
             return -1;
         if (token_is_pseudo_keyword(s, JS_ATOM_from)) {
-            module_name = js_parse_from_clause(s);
-            if (module_name == JS_ATOM_NULL)
-                return -1;
-            idx = add_req_module_entry(ctx, m, module_name);
-            JS_FreeAtom(ctx, module_name);
+            idx = js_parse_from_clause(s, m);
             if (idx < 0)
                 return -1;
             for(i = first_export; i < m->export_entries_count; i++) {
@@ -30063,11 +30266,7 @@ static __exception int js_parse_export(JSParseState *s)
             export_name = JS_DupAtom(ctx, s->token.u.ident.atom);
             if (next_token(s))
                 goto fail1;
-            module_name = js_parse_from_clause(s);
-            if (module_name == JS_ATOM_NULL)
-                goto fail1;
-            idx = add_req_module_entry(ctx, m, module_name);
-            JS_FreeAtom(ctx, module_name);
+            idx = js_parse_from_clause(s, m);
             if (idx < 0)
                 goto fail1;
             me = add_export_entry(s, m, JS_ATOM__star_, export_name,
@@ -30077,11 +30276,7 @@ static __exception int js_parse_export(JSParseState *s)
                 return -1;
             me->u.req_module_idx = idx;
         } else {
-            module_name = js_parse_from_clause(s);
-            if (module_name == JS_ATOM_NULL)
-                return -1;
-            idx = add_req_module_entry(ctx, m, module_name);
-            JS_FreeAtom(ctx, module_name);
+            idx = js_parse_from_clause(s, m);
             if (idx < 0)
                 return -1;
             if (add_star_export_entry(ctx, m, idx) < 0)
@@ -30187,6 +30382,14 @@ static __exception int js_parse_import(JSParseState *s)
             JS_FreeAtom(ctx, module_name);
             return -1;
         }
+        idx = add_req_module_entry(ctx, m, module_name);
+        JS_FreeAtom(ctx, module_name);
+        if (idx < 0)
+            return -1;
+        if (s->token.val == TOK_WITH) {
+            if (js_parse_with_clause(s, &m->req_module_entries[idx]))
+                return -1;
+        }
     } else {
         if (s->token.val == TOK_IDENT) {
             if (s->token.u.ident.is_reserved) {
@@ -30285,14 +30488,10 @@ static __exception int js_parse_import(JSParseState *s)
                 return -1;
         }
     end_import_clause:
-        module_name = js_parse_from_clause(s);
-        if (module_name == JS_ATOM_NULL)
+        idx = js_parse_from_clause(s, m);
+        if (idx < 0)
             return -1;
     }
-    idx = add_req_module_entry(ctx, m, module_name);
-    JS_FreeAtom(ctx, module_name);
-    if (idx < 0)
-        return -1;
     for(i = first_import; i < m->import_entries_count; i++)
         m->import_entries[i].req_module_idx = idx;
 
diff --git a/quickjs.h b/quickjs.h
index 60a8d49..c92afbc 100644
--- a/quickjs.h
+++ b/quickjs.h
@@ -936,12 +936,25 @@ typedef char *JSModuleNormalizeFunc(JSContext *ctx,
                                     const char *module_name, void *opaque);
 typedef JSModuleDef *JSModuleLoaderFunc(JSContext *ctx,
                                         const char *module_name, void *opaque);
-
+typedef JSModuleDef *JSModuleLoaderFunc2(JSContext *ctx,
+                                         const char *module_name, void *opaque,
+                                         JSValueConst attributes);
+/* return -1 if exception, 0 if OK */
+typedef int JSModuleCheckSupportedImportAttributes(JSContext *ctx, void *opaque,
+                                                   JSValueConst attributes);
+                                                   
 /* module_normalize = NULL is allowed and invokes the default module
    filename normalizer */
 void JS_SetModuleLoaderFunc(JSRuntime *rt,
                             JSModuleNormalizeFunc *module_normalize,
                             JSModuleLoaderFunc *module_loader, void *opaque);
+/* same as JS_SetModuleLoaderFunc but with attributes. if
+   module_check_attrs = NULL, no attribute checking is done. */
+void JS_SetModuleLoaderFunc2(JSRuntime *rt,
+                             JSModuleNormalizeFunc *module_normalize,
+                             JSModuleLoaderFunc2 *module_loader,
+                             JSModuleCheckSupportedImportAttributes *module_check_attrs,
+                             void *opaque);
 /* return the import.meta object of a module */
 JSValue JS_GetImportMeta(JSContext *ctx, JSModuleDef *m);
 JSAtom JS_GetModuleName(JSContext *ctx, JSModuleDef *m);
@@ -1119,7 +1132,10 @@ int JS_SetModuleExport(JSContext *ctx, JSModuleDef *m, const char *export_name,
                        JSValue val);
 int JS_SetModuleExportList(JSContext *ctx, JSModuleDef *m,
                            const JSCFunctionListEntry *tab, int len);
-
+/* associate a JSValue to a C module */
+int JS_SetModulePrivateValue(JSContext *ctx, JSModuleDef *m, JSValue val);
+JSValue JS_GetModulePrivateValue(JSContext *ctx, JSModuleDef *m);
+                        
 /* debug value output */
 
 typedef struct {
diff --git a/run-test262.c b/run-test262.c
index 3da79a0..be35834 100644
--- a/run-test262.c
+++ b/run-test262.c
@@ -836,13 +836,21 @@ static char *load_file(const char *filename, size_t *lenp)
     return buf;
 }
 
+static int json_module_init_test(JSContext *ctx, JSModuleDef *m)
+{
+    JSValue val;
+    val = JS_GetModulePrivateValue(ctx, m);
+    JS_SetModuleExport(ctx, m, "default", val);
+    return 0;
+}
+
 static JSModuleDef *js_module_loader_test(JSContext *ctx,
-                                          const char *module_name, void *opaque)
+                                          const char *module_name, void *opaque,
+                                          JSValueConst attributes)
 {
     size_t buf_len;
     uint8_t *buf;
     JSModuleDef *m;
-    JSValue func_val;
     char *filename, *slash, path[1024];
 
     // interpret import("bar.js") from path/to/foo.js as
@@ -864,15 +872,33 @@ static JSModuleDef *js_module_loader_test(JSContext *ctx,
         return NULL;
     }
 
-    /* compile the module */
-    func_val = JS_Eval(ctx, (char *)buf, buf_len, module_name,
-                       JS_EVAL_TYPE_MODULE | JS_EVAL_FLAG_COMPILE_ONLY);
-    js_free(ctx, buf);
-    if (JS_IsException(func_val))
-        return NULL;
-    /* the module is already referenced, so we must free it */
-    m = JS_VALUE_GET_PTR(func_val);
-    JS_FreeValue(ctx, func_val);
+    if (js_module_test_json(ctx, attributes)) {
+        /* compile as JSON */
+        JSValue val;
+        val = JS_ParseJSON(ctx, (char *)buf, buf_len, module_name);
+        js_free(ctx, buf);
+        if (JS_IsException(val))
+            return NULL;
+        m = JS_NewCModule(ctx, module_name, json_module_init_test);
+        if (!m) {
+            JS_FreeValue(ctx, val);
+            return NULL;
+        }
+        /* only export the "default" symbol which will contain the JSON object */
+        JS_AddModuleExport(ctx, m, "default");
+        JS_SetModulePrivateValue(ctx, m, val);
+    } else {
+        JSValue func_val;
+        /* compile the module */
+        func_val = JS_Eval(ctx, (char *)buf, buf_len, module_name,
+                           JS_EVAL_TYPE_MODULE | JS_EVAL_FLAG_COMPILE_ONLY);
+        js_free(ctx, buf);
+        if (JS_IsException(func_val))
+            return NULL;
+        /* the module is already referenced, so we must free it */
+        m = JS_VALUE_GET_PTR(func_val);
+        JS_FreeValue(ctx, func_val);
+    }
     return m;
 }
 
@@ -1587,7 +1613,7 @@ int run_test_buf(const char *filename, const char *harness, namelist_t *ip,
     JS_SetCanBlock(rt, can_block);
 
     /* loader for ES6 modules */
-    JS_SetModuleLoaderFunc(rt, NULL, js_module_loader_test, (void *)filename);
+    JS_SetModuleLoaderFunc2(rt, NULL, js_module_loader_test, NULL, (void *)filename);
 
     add_helpers(ctx);
 
@@ -1888,7 +1914,7 @@ int run_test262_harness_test(const char *filename, BOOL is_module)
     JS_SetCanBlock(rt, can_block);
 
     /* loader for ES6 modules */
-    JS_SetModuleLoaderFunc(rt, NULL, js_module_loader_test, (void *)filename);
+    JS_SetModuleLoaderFunc2(rt, NULL, js_module_loader_test, NULL, (void *)filename);
 
     add_helpers(ctx);
 
diff --git a/test262.conf b/test262.conf
index 02df380..809d416 100644
--- a/test262.conf
+++ b/test262.conf
@@ -116,9 +116,7 @@ for-of
 generators
 globalThis
 hashbang
-host-gc-required=skip
-import-assertions=skip
-import-attributes=skip
+import-attributes
 import-defer=skip
 import.meta
 Int16Array
@@ -144,7 +142,7 @@ Intl.Segmenter=skip
 IsHTMLDDA
 iterator-helpers=skip
 iterator-sequencing=skip
-json-modules=skip
+json-modules
 json-parse-with-source=skip
 json-superset
 legacy-regexp=skip