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LibJS/Bytecode: Make typeof return "undefined" on unresolvable IDs

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Previously it would throw instead of returning "undefined" for
`typeof Identifier` if Identifier does not exist.
This commit is contained in:
Luke Wilde 2022-06-11 23:12:22 +01:00 • committed by Ali Mohammad Pur
parent c0fadfb9b7
commit 482a827346
4 changed files with 55 additions and 1 deletions
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28
Userland/Libraries/LibJS/Bytecode/Op.cpp
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@ -764,6 +764,29 @@ ThrowCompletionOr<void> NewClass::execute_impl(Bytecode::Interpreter& interprete
return {};
}
// 13.5.3.1 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-typeof-operator-runtime-semantics-evaluation
ThrowCompletionOr<void> TypeofVariable::execute_impl(Bytecode::Interpreter& interpreter) const
{
// 1. Let val be the result of evaluating UnaryExpression.
auto const& string = interpreter.current_executable().get_identifier(m_identifier);
auto reference = TRY(interpreter.vm().resolve_binding(string));
// 2. If val is a Reference Record, then
// a. If IsUnresolvableReference(val) is true, return "undefined".
if (reference.is_unresolvable()) {
interpreter.accumulator() = js_string(interpreter.vm(), "undefined"sv);
return {};
}
// 3. Set val to ? GetValue(val).
auto value = TRY(reference.get_value(interpreter.global_object()));
// 4. NOTE: This step is replaced in section B.3.6.3.
// 5. Return a String according to Table 41.
interpreter.accumulator() = js_string(interpreter.vm(), value.typeof());
return {};
}
String Load::to_string_impl(Bytecode::Executable const&) const
{
return String::formatted("Load {}", m_src);
@ -1076,4 +1099,9 @@ String GetNewTarget::to_string_impl(Bytecode::Executable const&) const
return "GetNewTarget"sv;
}
String TypeofVariable::to_string_impl(Bytecode::Executable const& executable) const
{
return String::formatted("TypeofVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
}
}