Add API for deletion of object properties.

PR-URL: nodejs/node-addon-api#151
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jason Ginchereau <jasongin@microsoft.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

napi-inl.h

@@ -757,6 +757,28 @@ inline void Object::Set(const std::string& utf8name, double numberValue) {
   Set(utf8name.c_str(), Number::New(Env(), numberValue));
 }
 
+inline bool Object::Delete(napi_value key) {
+  bool result;
+  napi_status status = napi_delete_property(_env, _value, key, &result);
+  NAPI_THROW_IF_FAILED(_env, status, false);
+  return result;
+}
+
+inline bool Object::Delete(Value key) {
+  bool result;
+  napi_status status = napi_delete_property(_env, _value, key, &result);
+  NAPI_THROW_IF_FAILED(_env, status, false);
+  return result;
+}
+
+inline bool Object::Delete(const char* utf8name) {
+  return Delete(String::New(_env, utf8name));
+}
+
+inline bool Object::Delete(const std::string& utf8name) {
+  return Delete(String::New(_env, utf8name));
+}
+
 inline bool Object::Has(uint32_t index) const {
   bool result;
   napi_status status = napi_has_element(_env, _value, index, &result);
@@ -797,6 +819,13 @@ inline void Object::Set(uint32_t index, double numberValue) {
   Set(index, static_cast<napi_value>(Number::New(Env(), numberValue)));
 }
 
+inline bool Object::Delete(uint32_t index) {
+  bool result;
+  napi_status status = napi_delete_element(_env, _value, index, &result);
+  NAPI_THROW_IF_FAILED(_env, status, false);
+  return result;
+}
+
 inline Array Object::GetPropertyNames() {
   napi_value result;
   napi_status status = napi_get_property_names(_env, _value, &result);
@@ -1657,7 +1686,7 @@ inline Reference<T>& Reference<T>::operator =(Reference<T>&& other) {
 }
 
 template <typename T>
-inline Reference<T>::Reference(const Reference<T>& other) 
+inline Reference<T>::Reference(const Reference<T>& other)
   : _env(other._env), _ref(nullptr), _suppressDestruct(false) {
   HandleScope scope(_env);
 

napi.h

@@ -491,6 +491,26 @@ namespace Napi {
       double numberValue           ///< Property value
     );
 
+    /// Delete property.
+    bool Delete(
+      napi_value key ///< Property key primitive
+    );
+
+    /// Delete property.
+    bool Delete(
+      Value key ///< Property key
+    );
+
+    /// Delete property.
+    bool Delete(
+      const char* utf8name ///< UTF-8 encoded null-terminated property name
+    );
+
+    /// Delete property.
+    bool Delete(
+      const std::string& utf8name ///< UTF-8 encoded property name
+    );
+
     /// Checks whether an indexed property is present.
     bool Has(
       uint32_t index ///< Property / element index
@@ -537,6 +557,11 @@ namespace Napi {
       double numberValue ///< Property value
     );
 
+    /// Deletes an indexed property or array element.
+    bool Delete(
+      uint32_t index ///< Property / element index
+    );
+
     Array GetPropertyNames(); ///< Get all property names
 
     /// Defines a property on the object.

test/object.cc

@@ -102,6 +102,12 @@ void SetProperty(const CallbackInfo& info) {
   obj.Set(name, value);
 }
 
+Value DeleteProperty(const CallbackInfo& info) {
+  Object obj = info[0].As<Object>();
+  Name name = info[1].As<Name>();
+  return Boolean::New(info.Env(), obj.Delete(name));
+}
+
 Object InitObject(Env env) {
   Object exports = Object::New(env);
 
@@ -110,6 +116,7 @@ Object InitObject(Env env) {
   exports["defineValueProperty"] = Function::New(env, DefineValueProperty);
   exports["getProperty"] = Function::New(env, GetProperty);
   exports["setProperty"] = Function::New(env, SetProperty);
+  exports["deleteProperty"] = Function::New(env, DeleteProperty);
 
   return exports;
 }

test/object.js

@@ -82,6 +82,18 @@ function test(binding) {
     assert.strictEqual(obj.test, 1);
   }
 
+  {
+    const obj = { one: 1, two: 2 };
+    Object.defineProperty(obj, "three", {configurable: false, value: 3});
+    assert.strictEqual(binding.object.deleteProperty(obj, 'one'), true);
+    assert.strictEqual(binding.object.deleteProperty(obj, 'missing'), true);
+
+    /* Returns true for all cases except when the property is an own non-
+       configurable property, in which case, false is returned in non-strict mode. */
+    assert.strictEqual(binding.object.deleteProperty(obj, 'three'), false);
+    assert.deepStrictEqual(obj, { two: 2 });
+  }
+
   {
     const obj = {'one': 1, 'two': 2, 'three': 3};
     var arr = binding.object.GetPropertyNames(obj);
@@ -94,4 +106,7 @@ function test(binding) {
   assert.throws(() => {
     binding.object.setProperty(undefined, 'test', 1);
   }, /object was expected/);
+  assert.throws(() => {
+    binding.object.deleteProperty(undefined, 'test');
+  }, /object was expected/);
 }