Extending a base store for Vuex for multiple Vue applications / instances (with some examples).

actions.js

export const changeIsMobile = ({ commit }, isMobile) => {
    commit('setIsMobile', isMobile);
};

export const changeLoading = ({ commit }, loading) => {
    commit('setLoading', loading);
};

export const addError = ({ commit }, e) => {
    commit('updateAddError', e);
};

export const resetAllErrors = ({ commit }) => {
    commit('resetErrors');
};

BaseStore.js

import * as actions from './base-store/actions';
import * as mutations from './base-store/mutations';
import * as getters from './base-store/getters';

export default {
    state: {
        loading: false,
        isMobile: false,
        errors: []
    },
    getters,
    mutations,
    actions
}

getters.js

export const getIsMobile = (state) => {
    return state.isMobile;
}

export const getLoading = (state) => {
    return state.loading;
}

export const getErrors = (state) => {
    return state.errors;
}

mutations.js

export const setLoading = (state, loading) => {
    state.loading = loading;
}

export const setIsMobile = (state, isMobile) => {
    state.isMobile = isMobile;
}

export const updateAddError = (state, error) => {
    state.errors.push(error);
}

export const resetErrors = (state) => {
    state.errors = [];
}

store.js

....
import BaseStore from './path/to/resolve/BaseStore'
export const store = new Vuex.Store(Object.assign(
    {},
    BaseStore,
    { modules: { exampleModule1, exampleModule2 } }
));