feat: javascript helpers extension

fix #881

Author: alandefreitas

src/lib/Support/JavaScript.cpp

@@ -119,8 +119,10 @@ Value::~Value()
 }
 
 Value::Value(Value const& other)
-    : impl_(other.impl_), ctx_(other.ctx_), val_(to_handle(jerry_value_copy(to_js(other.val_))))
+    : impl_(other.impl_), ctx_(other.ctx_), val_(0)
 {
+    if (other.val_)
+        val_ = to_handle(jerry_value_copy(to_js(other.val_)));
 }
 
 Value::Value(Value&& other) noexcept
@@ -138,7 +140,7 @@ Value& Value::operator=(Value const& other)
         jerry_value_free(to_js(val_));
     impl_ = other.impl_;
     ctx_ = other.ctx_;
-    val_ = to_handle(jerry_value_copy(to_js(other.val_)));
+    val_ = other.val_ ? to_handle(jerry_value_copy(to_js(other.val_))) : 0;
     return *this;
 }
 
@@ -720,15 +722,24 @@ static dom::Value toDomValue(jerry_value_t v, std::shared_ptr<Context::Impl> con
     if (jerry_value_is_function(v))
     {
         // Wrap the JS function so it can be invoked from DOM helpers.
-        jerry_value_t fn = jerry_value_copy(v);
-        return dom::makeVariadicInvocable([fn, impl](dom::Array const& args) -> Expected<dom::Value, Error>
+        auto fnHandle = std::shared_ptr<jerry_value_t>(
+            new jerry_value_t(jerry_value_copy(v)),
+            [](jerry_value_t* h)
+            {
+                if (!h)
+                    return;
+                jerry_value_free(*h);
+                delete h;
+            });
+
+        return dom::makeVariadicInvocable([fnHandle, impl](dom::Array const& args) -> Expected<dom::Value, Error>
         {
             std::vector<jerry_value_t> jsArgs;
             jsArgs.reserve(args.size());
             for (auto const& a : args)
                 jsArgs.push_back(toJsValue(a, impl));
 
-            jerry_value_t ret = jerry_call(fn, jerry_undefined(), jsArgs.data(), jsArgs.size());
+            jerry_value_t ret = jerry_call(*fnHandle, jerry_undefined(), jsArgs.data(), jsArgs.size());
             for (auto& a : jsArgs) jerry_value_free(a);
             if (jerry_value_is_exception(ret))
             {