ImmutableJS for dummies

immutable.js

function reduce(state = Immutable.fromJS({
  items: {
    values: []
  }
}), action = null) {
  if(action) {
    switch(action.type) {
      case "ADD":
        return state.updateIn(['items','values'], (data) => data.push(action.payload));
      case "REMOVE":
        return state.updateIn(['items','values'], (data) => data.delete(data.findKey((item) => item.id === action.payload.id)))
      case "UPDATE":
        return state.updateIn(['items','values'], (data) => data.update(data.findKey((item) => item.id === action.payload.id), (item) => Object.assign({}, item, action.payload)))
    }
  }
  return state;
}

let state;

state = reduce(state, { type: "ADD", payload: { id: 1, value: Math.random() }});
state = reduce(state, { type: "ADD", payload: { id: 2, value: Math.random() }});
state = reduce(state, { type: "ADD", payload: { id: 3, value: Math.random() }});
state = reduce(state, { type: "UPDATE", payload: { id: 2, value: -1 }});
state = reduce(state, { type: "REMOVE", payload: { id: 3 }});
state.getIn(['items','values']).map(i => console.log(i.value));