app-1.ts

// Acciones
interface Action {
    type: string;
    payload?: any;
}

// const incrementadorAction: Action = {
//     type: 'INCREMENTAR'
// };


function reducer( state = 10, action: Action ) {

    switch ( action.type ) {

        case 'INCREMENTAR': 
            return state += 1;

        case 'DECREMENTAR': 
            return state -= 1;

        case 'MULTIPLICAR': 
            return state * action.payload;

        case 'DIVIDIR':
            return state / action.payload;


        default: 
            return state;
    }

}


// Usar el reducer

const incrementadorAction: Action = {
    type: 'INCREMENTAR'
};


console.log( reducer(10, incrementadorAction ) ); // 11


const decrementadorAction: Action = {
    type: 'DECREMENTAR'
};

console.log( reducer(10, decrementadorAction ) ); // 9


const multiplicarAction: Action = {
    type: 'MULTIPLICAR',
    payload: 2
};

console.log( reducer(10, multiplicarAction ) ); // 20


// Tarea
// dividirAction 
// payload

const dividirAction: Action = {
    type: 'DIVIDIR',
    payload: 2
};

console.log( reducer(10, dividirAction ) ); // 5