Introdution to redux

redux_intro.js

import Redux from 'redux';

console.clear();

// Action creators

const createPolicy = (name, amount) => {
    return {
        type: 'CREATE_POLICY',
        payload: {
            name, amount
        }
    };
};

const deletePolicy = name => {
    return {
        type: 'DELETE_POLICY',
        payload: {
            name
        }
    };
};

const createClaim = (name, amountOfMoneyToCollect) => {
    return {
        type: 'CREATE_CLAIM',
        payload: {
            name, amountOfMoneyToCollect
        }
    }
};

// Reducers

const claimsHistory = (oldListOfClaims = [], action) => {
    if (action.type === 'CREATE_CLAIM') {
        return [...oldListOfClaims, action.payload];
    }

    return oldListOfClaims;
};

const accounting = (bagOfMoney = 100, action) => {
    if (action.type === 'CREATE_CLAIM') {
        return bagOfMoney - action.payload.amountOfMoneyToCollect;
    }

    if (action.type === 'CREATE_POLICY') {
        return bagOfMoney + action.payload.amount;
    }

    return bagOfMoney;
};

const policies = (listOfPolicies = [], action) => {
    if (action.type === 'CREATE_POLICY') {
        return [...listOfPolicies, action.payload.name];
    }

    if (action.type === 'DELETE_POLICY') {
        return listOfPolicies.filter(name => name !== action.payload.name);
    }

    return listOfPolicies;
};

const {createStore, combineReducers} = Redux;

const ourDepartments = combineReducers({
    accounting: accounting,
    claimsHistory: claimsHistory,
    policies: policies
});

const store = createStore(ourDepartments);

store.dispatch(createPolicy('Alex', 20));
store.dispatch(createPolicy('Jim', 30));
store.dispatch(createPolicy('Bob', 40));

store.dispatch(createClaim('Alex', 120));
store.dispatch(createClaim('Jim', 50));

store.dispatch(deletePolicy('Bob'));

console.log(store.getState());