3 files changed, 25 insertions, 5 deletions
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
index 3ae2894f6d..7d6502917c 100644
--- a/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp
@@ -98,7 +98,17 @@ void ObjectEnvironment::set_mutable_binding(GlobalObject& global_object, FlyStri
         global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
         return;
     }
-    m_binding_object.set(name, value, strict ? Object::ShouldThrowExceptions::Yes : Object::ShouldThrowExceptions::No);
+
+    auto result = m_binding_object.set(name, value, strict ? Object::ShouldThrowExceptions::Yes : Object::ShouldThrowExceptions::No);
+
+    // Note: Nothing like this in the spec, this is here to produce nicer errors instead of the generic one thrown by Object::set().
+    if (!result && strict) {
+        auto property = m_binding_object.internal_get_own_property(name);
+        if (property.has_value() && !property->writable.value_or(true)) {
+            vm.clear_exception();
+            vm.throw_exception<TypeError>(global_object, ErrorType::DescWriteNonWritable, name);
+        }
+    }
 }
 
 // 9.1.1.2.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-getbindingvalue-n-s
diff --git a/Userland/Libraries/LibJS/Runtime/Reference.cpp b/Userland/Libraries/LibJS/Runtime/Reference.cpp
index bb6d3620b1..adae50a022 100644
--- a/Userland/Libraries/LibJS/Runtime/Reference.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Reference.cpp
@@ -50,6 +50,7 @@ void Reference::put_value(GlobalObject& global_object, Value value)
     }
 
     VERIFY(m_base_type == BaseType::Environment);
+    // FIXME: This entire following section is 100% not spec-compliant.
     auto existing_variable = m_base_environment->get_from_environment(m_name.as_string());
     Variable variable {
         .value = value,
@@ -66,10 +67,11 @@ void Reference::put_value(GlobalObject& global_object, Value value)
     if (vm.exception())
         return;
 
-    if (!succeeded && m_strict) {
-        // FIXME: This is a hack and will disappear when we support proper variable bindings.
-        vm.throw_exception<TypeError>(global_object, ErrorType::DescWriteNonWritable, m_name);
-        return;
+    if (!succeeded) {
+        if (m_base_environment->has_binding(m_name.as_string())) {
+            m_base_environment->set_mutable_binding(global_object, m_name.as_string(), value, is_strict());
+            return;
+        }
     }
 }
 
@@ -98,8 +100,11 @@ Value Reference::get_value(GlobalObject& global_object, bool throw_if_undefined)
     }
 
     VERIFY(m_base_type == BaseType::Environment);
+    // FIXME: This entire section is 100% not spec-compliant.
     auto value = m_base_environment->get_from_environment(m_name.as_string());
     if (!value.has_value()) {
+        if (m_base_environment->has_binding(m_name.as_string()))
+            return m_base_environment->get_binding_value(global_object, m_name.as_string(), is_strict());
         if (!throw_if_undefined) {
             // FIXME: This is an ad-hoc hack for the `typeof` operator until we support proper variable bindings.
             return js_undefined();
@@ -168,6 +173,9 @@ bool Reference::delete_(GlobalObject& global_object)
     VERIFY(m_base_type == BaseType::Environment);
 
     //    c. Return ? base.DeleteBinding(ref.[[ReferencedName]]).
+    if (m_base_environment->has_binding(m_name.as_string()))
+        return m_base_environment->delete_binding(global_object, m_name.as_string());
+
     // FIXME: This is ad-hoc, we should be calling DeleteBinding.
     return m_base_environment->delete_from_environment(m_name.as_string());
 }
diff --git a/Userland/Libraries/LibJS/Runtime/VM.cpp b/Userland/Libraries/LibJS/Runtime/VM.cpp
index 9bbbce248b..d470470ab1 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.cpp
+++ b/Userland/Libraries/LibJS/Runtime/VM.cpp
@@ -417,6 +417,8 @@ Reference VM::get_identifier_reference(Environment* environment, FlyString name,
         auto possible_match = environment->get_from_environment(name);
         if (possible_match.has_value())
             return Reference { *environment, move(name), strict };
+        if (environment->has_binding(name))
+            return Reference { *environment, move(name), strict };
     }
 
     auto& global_environment = interpreter().realm().global_environment();