n-api: add napi_has_own_property()

Refs: #13925 PR-URL: #14063 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
nodejs · Jul 19, 2017 · 1b7a0cd · 1b7a0cd
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diff --git a/doc/api/n-api.md b/doc/api/n-api.md
@@ -2298,6 +2298,29 @@ Returns `napi_ok` if the API succeeded.
 This API attempts to delete the `key` own property from `object`.
 
 
+#### *napi_has_own_property*
+<!-- YAML
+added: REPLACEME
+-->
+```C
+napi_status napi_has_own_property(napi_env env,
+                                  napi_value object,
+                                  napi_value key,
+                                  bool* result);
+```
+
+- `[in] env`: The environment that the N-API call is invoked under.
+- `[in] object`: The object to query.
+- `[in] key`: The name of the own property whose existence to check.
+- `[out] result`: Whether the own property exists on the object or not.
+
+Returns `napi_ok` if the API succeeded.
+
+This API checks if the Object passed in has the named own property. `key` must
+be a string or a Symbol, or an error will be thrown. N-API will not perform any
+conversion between data types.
+
+
 #### *napi_set_named_property*
 <!-- YAML
 added: v8.0.0
@@ -3102,6 +3125,7 @@ support it:
 [`napi_get_element`]: #n_api_napi_get_element
 [`napi_get_property`]: #n_api_napi_get_property
 [`napi_has_property`]: #n_api_napi_has_property
+[`napi_has_own_property`]: #n_api_napi_has_own_property
 [`napi_set_property`]: #n_api_napi_set_property
 [`napi_get_reference_value`]: #n_api_napi_get_reference_value
 [`napi_is_error`]: #n_api_napi_is_error

diff --git a/src/node_api.cc b/src/node_api.cc
@@ -1042,6 +1042,27 @@ napi_status napi_delete_property(napi_env env,
   return GET_RETURN_STATUS(env);
 }
 
+NAPI_EXTERN napi_status napi_has_own_property(napi_env env,
+                                              napi_value object,
+                                              napi_value key,
+                                              bool* result) {
+  NAPI_PREAMBLE(env);
+  CHECK_ARG(env, key);
+
+  v8::Isolate* isolate = env->isolate;
+  v8::Local<v8::Context> context = isolate->GetCurrentContext();
+  v8::Local<v8::Object> obj;
+
+  CHECK_TO_OBJECT(env, context, obj, object);
+  v8::Local<v8::Value> k = v8impl::V8LocalValueFromJsValue(key);
+  RETURN_STATUS_IF_FALSE(env, k->IsName(), napi_name_expected);
+  v8::Maybe<bool> has_maybe = obj->HasOwnProperty(context, k.As<v8::Name>());
+  CHECK_MAYBE_NOTHING(env, has_maybe, napi_generic_failure);
+  *result = has_maybe.FromMaybe(false);
+
+  return GET_RETURN_STATUS(env);
+}
+
 napi_status napi_set_named_property(napi_env env,
                                     napi_value object,
                                     const char* utf8name,

diff --git a/src/node_api.h b/src/node_api.h
@@ -230,6 +230,10 @@ NAPI_EXTERN napi_status napi_delete_property(napi_env env,
                                              napi_value object,
                                              napi_value key,
                                              bool* result);
+NAPI_EXTERN napi_status napi_has_own_property(napi_env env,
+                                              napi_value object,
+                                              napi_value key,
+                                              bool* result);
 NAPI_EXTERN napi_status napi_set_named_property(napi_env env,
                                           napi_value object,
                                           const char* utf8name,

diff --git a/test/addons-napi/test_object/test.js b/test/addons-napi/test_object/test.js
@@ -50,6 +50,40 @@ assert.strictEqual(newObject.test_string, 'test string');
                      Object.prototype.toString);
 }
 
+{
+  // Verify that napi_has_own_property() fails if property is not a name.
+  [true, false, null, undefined, {}, [], 0, 1, () => {}].forEach((value) => {
+    assert.throws(() => {
+      test_object.HasOwn({}, value);
+    }, /^Error: A string or symbol was expected$/);
+  });
+}
+
+{
+  // Verify that napi_has_own_property() does not walk the prototype chain.
+  const symbol1 = Symbol();
+  const symbol2 = Symbol();
+
+  function MyObject() {
+    this.foo = 42;
+    this.bar = 43;
+    this[symbol1] = 44;
+  }
+
+  MyObject.prototype.bar = 45;
+  MyObject.prototype.baz = 46;
+  MyObject.prototype[symbol2] = 47;
+
+  const obj = new MyObject();
+
+  assert.strictEqual(test_object.HasOwn(obj, 'foo'), true);
+  assert.strictEqual(test_object.HasOwn(obj, 'bar'), true);
+  assert.strictEqual(test_object.HasOwn(obj, symbol1), true);
+  assert.strictEqual(test_object.HasOwn(obj, 'baz'), false);
+  assert.strictEqual(test_object.HasOwn(obj, 'toString'), false);
+  assert.strictEqual(test_object.HasOwn(obj, symbol2), false);
+}
+
 {
   // test_object.Inflate increases all properties by 1
   const cube = {

diff --git a/test/addons-napi/test_object/test_object.c b/test/addons-napi/test_object/test_object.c
@@ -86,6 +86,34 @@ napi_value Has(napi_env env, napi_callback_info info) {
   return ret;
 }
 
+napi_value HasOwn(napi_env env, napi_callback_info info) {
+  size_t argc = 2;
+  napi_value args[2];
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, args, NULL, NULL));
+
+  NAPI_ASSERT(env, argc == 2, "Wrong number of arguments");
+
+  napi_valuetype valuetype0;
+  NAPI_CALL(env, napi_typeof(env, args[0], &valuetype0));
+
+  NAPI_ASSERT(env, valuetype0 == napi_object,
+    "Wrong type of arguments. Expects an object as first argument.");
+
+  // napi_valuetype valuetype1;
+  // NAPI_CALL(env, napi_typeof(env, args[1], &valuetype1));
+  //
+  // NAPI_ASSERT(env, valuetype1 == napi_string || valuetype1 == napi_symbol,
+  //   "Wrong type of arguments. Expects a string or symbol as second.");
+
+  bool has_property;
+  NAPI_CALL(env, napi_has_own_property(env, args[0], args[1], &has_property));
+
+  napi_value ret;
+  NAPI_CALL(env, napi_get_boolean(env, has_property, &ret));
+
+  return ret;
+}
+
 napi_value Delete(napi_env env, napi_callback_info info) {
   size_t argc = 2;
   napi_value args[2];
@@ -196,6 +224,7 @@ void Init(napi_env env, napi_value exports, napi_value module, void* priv) {
     DECLARE_NAPI_PROPERTY("Get", Get),
     DECLARE_NAPI_PROPERTY("Set", Set),
     DECLARE_NAPI_PROPERTY("Has", Has),
+    DECLARE_NAPI_PROPERTY("HasOwn", HasOwn),
     DECLARE_NAPI_PROPERTY("Delete", Delete),
     DECLARE_NAPI_PROPERTY("New", New),
     DECLARE_NAPI_PROPERTY("Inflate", Inflate),