Is there a way to set the internalId of a localStorageProxy to an attribute of the model like the id?

I tried the following but there occurs an error:
Code:
myStore = new Ext.data.Store({
    model: "MyModel",
    storeId: 'myStore ',
    sorters: 'date',
    proxy: {
        id: 'myStore',
        type: 'localstorage',
        internalId: id,
        reader: {type: 'json'},
        writer: {type: 'json'}
    }
});
The error, which occur is:
Uncaught ReferenceError: id is not defined