4 files changed, 49 insertions, 41 deletions

diff --git a/Libraries/LibJS/Runtime/Object.cpp b/Libraries/LibJS/Runtime/Object.cpp
index 5ed464624c..331f3b3704 100644
--- a/Libraries/LibJS/Runtime/Object.cpp
+++ b/Libraries/LibJS/Runtime/Object.cpp
@@ -836,48 +836,30 @@ bool Object::has_own_property(const PropertyName& property_name) const
     return shape().lookup(property_name.to_string_or_symbol()).has_value();
 }
 
-Value Object::to_primitive(Value::PreferredType preferred_type) const
+Value Object::ordinary_to_primitive(Value::PreferredType preferred_type) const
 {
-    Value result = js_undefined();
+    ASSERT(preferred_type == Value::PreferredType::String || preferred_type == Value::PreferredType::Number);
 
-    switch (preferred_type) {
-    case Value::PreferredType::Default:
-    case Value::PreferredType::Number: {
-        result = value_of();
-        if (result.is_object()) {
-            result = to_string();
-        }
-        break;
-    }
-    case Value::PreferredType::String: {
-        result = to_string();
-        if (result.is_object())
-            result = value_of();
-        break;
-    }
-    }
+    auto& vm = this->vm();
 
-    ASSERT(!result.is_object());
-    return result;
-}
+    Vector<FlyString, 2> method_names;
+    if (preferred_type == Value::PreferredType::String)
+        method_names = { vm.names.toString, vm.names.valueOf };
+    else
+        method_names = { vm.names.valueOf, vm.names.toString };
 
-Value Object::to_string() const
-{
-    auto& vm = this->vm();
-    auto to_string_property = get(vm.names.toString);
-    if (to_string_property.is_function()) {
-        auto& to_string_function = to_string_property.as_function();
-        auto to_string_result = vm.call(to_string_function, const_cast<Object*>(this));
-        if (to_string_result.is_object())
-            vm.throw_exception<TypeError>(global_object(), ErrorType::Convert, "object", "string");
+    for (auto& method_name : method_names) {
+        auto method = get(method_name);
         if (vm.exception())
             return {};
-        auto* string = to_string_result.to_primitive_string(global_object());
-        if (vm.exception())
-            return {};
-        return string;
+        if (method.is_function()) {
+            auto result = vm.call(method.as_function(), const_cast<Object*>(this));
+            if (!result.is_object())
+                return result;
+        }
     }
-    return js_string(vm, String::formatted("[object {}]", class_name()));
+    vm.throw_exception<TypeError>(global_object(), ErrorType::Convert, "object", preferred_type == Value::PreferredType::String ? "string" : "number");
+    return {};
 }
 
 Value Object::invoke(const StringOrSymbol& property_name, Optional<MarkedValueList> arguments)
diff --git a/Libraries/LibJS/Runtime/Object.h b/Libraries/LibJS/Runtime/Object.h
index a1d76957a3..93e9daac69 100644
--- a/Libraries/LibJS/Runtime/Object.h
+++ b/Libraries/LibJS/Runtime/Object.h
@@ -140,8 +140,7 @@ public:
     virtual bool prevent_extensions();
 
     virtual Value value_of() const { return Value(const_cast<Object*>(this)); }
-    virtual Value to_primitive(Value::PreferredType preferred_type = Value::PreferredType::Default) const;
-    virtual Value to_string() const;
+    virtual Value ordinary_to_primitive(Value::PreferredType preferred_type) const;
 
     Value get_direct(size_t index) const { return m_storage[index]; }
 
diff --git a/Libraries/LibJS/Runtime/Value.cpp b/Libraries/LibJS/Runtime/Value.cpp
index 953a3b70ad..a0b6a4f96d 100644
--- a/Libraries/LibJS/Runtime/Value.cpp
+++ b/Libraries/LibJS/Runtime/Value.cpp
@@ -168,7 +168,7 @@ String Value::to_string(GlobalObject& global_object) const
     case Type::BigInt:
         return m_value.as_bigint->big_integer().to_base10();
     case Type::Object: {
-        auto primitive_value = as_object().to_primitive(PreferredType::String);
+        auto primitive_value = to_primitive(PreferredType::String);
         if (global_object.vm().exception())
             return {};
         return primitive_value.to_string(global_object);
@@ -205,8 +205,12 @@ bool Value::to_boolean() const
 
 Value Value::to_primitive(PreferredType preferred_type) const
 {
-    if (is_object())
-        return as_object().to_primitive(preferred_type);
+    if (is_object()) {
+        // FIXME: Also support @@toPrimitive
+        if (preferred_type == PreferredType::Default)
+            preferred_type = PreferredType::Number;
+        return as_object().ordinary_to_primitive(preferred_type);
+    }
     return *this;
 }
 
@@ -277,7 +281,7 @@ Value Value::to_number(GlobalObject& global_object) const
         global_object.vm().throw_exception<TypeError>(global_object, ErrorType::Convert, "BigInt", "number");
         return {};
     case Type::Object: {
-        auto primitive = m_value.as_object->to_primitive(PreferredType::Number);
+        auto primitive = to_primitive(PreferredType::Number);
         if (global_object.vm().exception())
             return {};
         return primitive.to_number(global_object);
diff --git a/Libraries/LibJS/Tests/ordinary-to-primitive.js b/Libraries/LibJS/Tests/ordinary-to-primitive.js
new file mode 100644
index 0000000000..176beadb76
--- /dev/null
+++ b/Libraries/LibJS/Tests/ordinary-to-primitive.js
@@ -0,0 +1,23 @@
+test("object with custom toString", () => {
+    const o = { toString: () => "foo" };
+    expect(o + "bar").toBe("foobar");
+    expect([o, "bar"].toString()).toBe("foo,bar");
+});
+
+test("object with uncallable toString and custom valueOf", () => {
+    const o = { toString: undefined, valueOf: () => "foo" };
+    expect(o + "bar").toBe("foobar");
+    expect([o, "bar"].toString()).toBe("foo,bar");
+});
+
+test("object with custom valueOf", () => {
+    const o = { valueOf: () => 42 };
+    expect(Number(o)).toBe(42);
+    expect(o + 1).toBe(43);
+});
+
+test("object with uncallable valueOf and custom toString", () => {
+    const o = { valueOf: undefined, toString: () => "42" };
+    expect(Number(o)).toBe(42);
+    expect(o + 1).toBe("421");
+});