I agree with user1628461, but if your application grows, it can be problematic to repeatedly pass the store as an argument.
A possibility you have is to first initialise your store, to then pass it as parameter when initialising your helper class.
This way you can save a reference to the store, its observables, and access it when needed. See example:
App.jsx
import Store from './store.jsx'
import Helper from './helper.jsx'
const myStore = new Store();
const myHelper = new Helper(myStore);
myHelper.doSomething();
helper.jsx
export default class Helper {
constructor(store){
this.store = store;
}
doSomething() {
// do something with the store
this.store.useAction();
this.store.anObservable = 'modified';
}
}