How to use the pscript.JSString function in pscript

else:
                    # Import from another module
                    self._import(mod_name, val.__name__, name)

        elif isinstance(val, type) and issubclass(val, bsdf.Extension):
            # A bit hacky mechanism to define BSDF extensions that also work in JS.
            # todo: can we make this better? See also app/_component2.py (issue #429)
            js = 'var %s = {name: "%s"' % (name, val.name)
            for mname in ('match', 'encode', 'decode'):
                func = getattr(val, mname + '_js')
                funccode = py2js(func, indent=1, inline_stdlib=False, docstrings=False)
                js += ',\n    ' + mname + ':' + funccode.split('=', 1)[1].rstrip(' \n;')
                self._collect_dependencies(funccode, _dep_stack)
            js += '};\n'
            js += 'serializer.add_extension(%s);\n' % name
            js = JSString(js)
            js.meta = funccode.meta
            self._pscript_code[name] = js
            self._deps.setdefault('flexx.app._clientcore',
                                 ['flexx.app._clientcore']).append('serializer')

        elif isinstance(val, pscript_types) and hasattr(val, '__module__'):
            # Looks like something we can convert using PScript
            mod_name = get_mod_name(val)
            if mod_name == self.name:
                # Define here
                try:
                    js = py2js(val, inline_stdlib=False, docstrings=False)
                except Exception as err:
                    t = 'JS in "%s" uses %r but cannot transpile it with PScript:\n%s'
                    raise ValueError(t % (self.filename, name, str(err)))
                self._provided_names.add(name)

def _get_js_of_base_classes(cls):
        """ Get JS for BaseAppComponent, LocalComponent, and ProxyComponent.
        """
        c1 = create_js_component_class(BaseAppComponent, 'BaseAppComponent',
                                       'Component.prototype')
        c2 = create_js_component_class(LocalComponent, 'LocalComponent',
                                       'BaseAppComponent.prototype')
        c3 = create_js_component_class(ProxyComponent, 'ProxyComponent',
                                       'BaseAppComponent.prototype')
        c4 = create_js_component_class(StubComponent, 'StubComponent',
                                       'BaseAppComponent.prototype')
        meta = c1.meta
        for k in ['vars_unknown', 'vars_global', 'std_functions', 'std_methods']:
            for c in (c2, c3, c4):
                meta[k].update(c.meta[k])
        js = JSString('\n'.join([c1, c2, c3, c4]))
        js.meta = meta
        return js

def attach_meta(self, s):
        s = JSString(s)
        s.meta = self.meta
        return s

# Add this class
        c = create_js_component_class(cls.JS, cls_name, base_class_name)
        meta = c.meta
        code.append(c)
        # code.append(c.replace('var %s =' % cls_name,
        #                   'var %s = flexx.classes.%s =' % (cls_name, cls_name), 1))

        # Add JS version of the base classes - but only once
        if cls.__name__ == 'JsComponent':
            c = cls._get_js_of_base_classes()
            for k in ['vars_unknown', 'vars_global', 'std_functions', 'std_methods']:
                meta[k].update(c.meta[k])
            code.insert(0, c)

        # Return with meta info
        js = JSString('\n'.join(code))
        js.meta = meta
        return js