{
  6:00AM: ['Get up', 'Make the bed', 'Brush my teeth'],
  6:45AM: ['Take a shower'],
  7:15AM: ['Have breakfast', 'Leave for school']
}

[
  {
    "id": 1,
    "day": "Monday",
    "activities": "6:00AM - Get up, Make the bed, Brush my teeth. 6:45AM - Take a shower. 7:15AM - Have breakfast, Leave for school."
  },
  {
    "id": 2,
    "day": "Tuesday",
    "activities": "6:00AM - Get up, Make the bed, Brush my teeth. 6:45AM - Take a shower. 7:15AM - Have breakfast, Leave for school."
  }
]

let activities = [];

/* My function */
private splitter() {
  // const activities holds just the array of strings
  const activities = this.itinerary.map(item => {
    return item.activities;
  });

  let result = {}; // The object that will hold the transformed string for each loop
  const res = activities.map(str => {
    for (result of str.split('.').map(x => x.trim())) {
      if (result) {
        const [time, actions] = str.split(' - ');
        result[time] = actions.split(',').map(x => x.trim());
      }
    }
    return result;
  });

  return res; // The final array with the transformed strings (now objects) as values
}

[
    {
      6:00AM: ['Get up', 'Make the bed', 'Brush my teeth'],
      6:45AM: ['Take a shower'],
      7:15AM: ['Have breakfast', 'Leave for school']
    },
    {
      6:00AM: ['Get up', 'Make the bed', 'Brush my teeth'],
      6:45AM: ['Take a shower'],
      7:15AM: ['Have breakfast', 'Leave for school']
    }
]

Uncaught (in promise): TypeError: Cannot create property '6:00AM' on string '6:00AM - Get up, Make the bed, Brush my teeth.'

const str = "6:00AM - Get up, Make the bed, Brush my teeth. 6:45AM - Take a shower. 7:15AM - Have breakfast, Leave for school."

sentences = {};
// split the string on periods, and trim each sentence
for (sentence of str.split('.').map(x => x.trim())) {
    // you end up with a completely empty sentence when the last
    // sentence ends in a period, which is uninteresting
    if (sentence) {
        // split each sentence on a hyphen, and assume the first
        // element is time and the second is actions
        let [time, actions] = sentence.split(' - ');

        // split the actions string on commas and trim whitespace;
        // store that in our sentences object
        sentences[time] = actions.split(',').map(x => x.trim());
    }
}

{ '6:00AM': [ 'Get up', 'Make the bed', 'Brush my teeth' ],
  '6:45AM': [ 'Take a shower' ],
  '7:15AM': [ 'Have breakfast', 'Leave for school' ] }

const string = "6:00AM - Get up, Make the bed, Brush my teeth. 6:45AM - Take a shower. 7:15AM - Have breakfast, Leave for school."
const firstSplit = string.split(".");

const secondSplit = firstSplit.map(each => each.split(" - "))

const almostThere = secondSplit.reduce((object, subarray) => {
  object[subarray[0]] = subarray[1]
  return object
}, {})

{
  6:00AM: "Get up, Make the bed, Brush my teeth",
  6:45AM: "Take a shower",
  7:15AM: "Have breakfast, Leave for school"
}

const yeay = secondSplit.reduce((object, subarray) => {
  object[subarray[0]] = subarray[1].split(", ")
}, {})

const firstSplit = string.split(".")
 .map(each => each.split(" - "))
 .reduce((object, subarray) => {
  object[subarray[0]] = subarray[1].split(", ")
  return object
}, {})

const yeay = string.split(".")
 .reduce((object, hourAndChores) => {
    const splittedHourAndChores = hourAndChores.split(" - ");
    object[splittedHourAndChores[0]] = splittedHourAndChores[1].split(", ")
    return object
}, {})