diff --git a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h index f4fcf82b2a..8b11a0faa8 100644 --- a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h +++ b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h @@ -23,6 +23,7 @@ M(Convert, "Cannot convert {} to {}") \ M(ConvertUndefinedToObject, "Cannot convert undefined to object") \ M(DescChangeNonConfigurable, "Cannot change attributes of non-configurable property '{}'") \ + M(DescWriteNonWritable, "Cannot write to non-writable property '{}'") \ M(DivisionByZero, "Division by zero") \ M(FunctionArgsNotObject, "Argument array must be an object") \ M(GetCapabilitiesExecutorCalledMultipleTimes, "GetCapabilitiesExecutor was called multiple times") \ diff --git a/Userland/Libraries/LibJS/Runtime/Object.cpp b/Userland/Libraries/LibJS/Runtime/Object.cpp index c7fa05b863..4667eed1d2 100644 --- a/Userland/Libraries/LibJS/Runtime/Object.cpp +++ b/Userland/Libraries/LibJS/Runtime/Object.cpp @@ -637,6 +637,8 @@ bool Object::put_own_property(const StringOrSymbol& property_name, Value value, auto value_here = m_storage[metadata.value().offset]; if (!new_property && mode == PutOwnPropertyMode::Put && !value_here.is_accessor() && !metadata.value().attributes.is_writable()) { dbgln_if(OBJECT_DEBUG, "Disallow write to non-writable property"); + if (throw_exceptions && vm().in_strict_mode()) + vm().throw_exception(global_object(), ErrorType::DescWriteNonWritable, property_name.to_display_string()); return false; } diff --git a/Userland/Libraries/LibJS/Tests/non-writable-assignment.js b/Userland/Libraries/LibJS/Tests/non-writable-assignment.js new file mode 100644 index 0000000000..2674cf6221 --- /dev/null +++ b/Userland/Libraries/LibJS/Tests/non-writable-assignment.js @@ -0,0 +1,12 @@ +test("normal mode", () => { + expect(() => { + NaN = 5; // NaN is a non-writable global variable + }).not.toThrow(); +}); + +test("strict mode", () => { + expect(() => { + "use strict"; + NaN = 5; // NaN is a non-writable global variable + }).toThrowWithMessage(TypeError, "Cannot write to non-writable property 'NaN'"); +});