JSValue JSInjectedScriptHost::subtype(ExecState* exec)
{
    if (exec->argumentCount() < 1)
        return jsUndefined();

    JSValue value = exec->uncheckedArgument(0);
    if (value.isString())
        return exec->vm().smallStrings.stringString();
    if (value.isBoolean())
        return exec->vm().smallStrings.booleanString();
    if (value.isNumber())
        return exec->vm().smallStrings.numberString();
    if (value.isSymbol())
        return exec->vm().smallStrings.symbolString();

    JSObject* object = asObject(value);
    if (object) {
        if (object->isErrorInstance())
            return jsNontrivialString(exec, ASCIILiteral("error"));

        // Consider class constructor functions class objects.
        JSFunction* function = jsDynamicCast<JSFunction*>(value);
        if (function && function->isClassConstructorFunction())
            return jsNontrivialString(exec, ASCIILiteral("class"));
    }

    if (value.inherits(JSArray::info()))
        return jsNontrivialString(exec, ASCIILiteral("array"));
    if (value.inherits(DirectArguments::info()) || value.inherits(ScopedArguments::info()))
        return jsNontrivialString(exec, ASCIILiteral("array"));

    if (value.inherits(DateInstance::info()))
        return jsNontrivialString(exec, ASCIILiteral("date"));
    if (value.inherits(RegExpObject::info()))
        return jsNontrivialString(exec, ASCIILiteral("regexp"));

    if (value.inherits(JSMap::info()))
        return jsNontrivialString(exec, ASCIILiteral("map"));
    if (value.inherits(JSSet::info()))
        return jsNontrivialString(exec, ASCIILiteral("set"));
    if (value.inherits(JSWeakMap::info()))
        return jsNontrivialString(exec, ASCIILiteral("weakmap"));
    if (value.inherits(JSWeakSet::info()))
        return jsNontrivialString(exec, ASCIILiteral("weakset"));

    if (value.inherits(JSArrayIterator::info())
        || value.inherits(JSMapIterator::info())
        || value.inherits(JSSetIterator::info())
        || value.inherits(JSStringIterator::info()))
        return jsNontrivialString(exec, ASCIILiteral("iterator"));

    if (value.inherits(JSInt8Array::info()) || value.inherits(JSInt16Array::info()) || value.inherits(JSInt32Array::info()))
        return jsNontrivialString(exec, ASCIILiteral("array"));
    if (value.inherits(JSUint8Array::info()) || value.inherits(JSUint16Array::info()) || value.inherits(JSUint32Array::info()))
        return jsNontrivialString(exec, ASCIILiteral("array"));
    if (value.inherits(JSFloat32Array::info()) || value.inherits(JSFloat64Array::info()))
        return jsNontrivialString(exec, ASCIILiteral("array"));

    return impl().subtype(exec, value);
}