group objects in array based on value of key in object

Question

I have the following data that I want to sort based on the date - not including the timestamp.

NOTE: I have access to moment for this task.

Answer 1

You could take just a slice from the date and later take the entries of the object and map new key/values.

 const
     data = [{ fixture: "AC v Inter", kickOffTime: "2018-06-14T15:00:00Z" }, { fixture: "DC v NYC", kickOffTime: "2018-06-15T12:00:00Z" }, { fixture: "AFC v LPC", kickOffTime: "2018-06-15T15:00:00Z" }, { fixture: "DTA v MC", kickOffTime: "2018-06-15T18:00:00Z" }, { fixture: "LAC v GC", kickOffTime: "2018-06-16T18:00:00Z" }];
     result = Object
        .entries(data.reduce((r, a) => {
            var key = a.kickOffTime.slice(0, 10);
            r[key] = r[key] || [];
            r[key].push(a);
            return r;
        }, Object.create(null)))
        .map(([date, fixtures]) => ({ date, fixtures }));

console.log(result);

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Answer 2

You can group the array using reduce into an object. Using Object.values you can convert the object into array.

const data = [{
    "fixture": "AC v Inter",
    "kickOffTime": "2018-06-14T15:00:00Z",
  },
  {
    "fixture": "DC v NYC",
    "kickOffTime": "2018-06-15T12:00:00Z",
  },
  {
    "fixture": "AFC v LPC",
    "kickOffTime": "2018-06-15T15:00:00Z",
  },
  {
    "fixture": "DTA v MC",
    "kickOffTime": "2018-06-15T18:00:00Z",
  },
  {
    "fixture": "LAC v GC",
    "kickOffTime": "2018-06-16T18:00:00Z",
  }
];

const result = Object.values(data.reduce((c, v) => {
  let t = v['kickOffTime'].split('T', 1)[0];
  c[t] = c[t] || {date: t,fixtures: []}
  c[t].fixtures.push(v);
  return c;
}, {}));

console.log(result);