Divide array elements into groups based on their values in JavaScript

Within my JavaScript API, I have received a result that requires me to group elements by date in order to perform further calculations. The result is as follows: 

[
  "2020-01-24 08:00:00",
  "2020-01-23 14:00:00",
  "2020-01-23 12:00:00",
  "2020-01-23 09:00:00",
  "2020-01-22 09:00:00",
  "2020-01-22 13:00:00"
]

The grouping should be done like this : 

[ "2020-01-24": 1 value,
  "2020-01-23": 3 value,
  "2020-01-22": 2 value ]

In addition, I also need to search within the array and extract any values with a count of >= 3 to place them in another array.

javascriptarrays

Answer №1

Utilize Array.prototype.reduce to iterate through the array and increment the value in the accumulator.

var y = [
  "2020-02-15 10:00:00",
  "2020-02-14 09:00:00",
  "2020-02-14 12:00:00",
  "2020-02-13 08:00:00",
  "2020-02-13 11:00:00",
  "2020-02-12 16:00:00"
];

const modifiedDate = y.reduce((temp,elem) => {
  const dateVar = elem.split(" ")[0];
  temp[dateVar] = (temp[dateVar] || 0) + 1;
  return temp;
}, {});

console.log(modifiedDate);

Answer №2

Take a look at https://lodash.com/docs/4.17.15#groupBy for assistance.


const dates = [
  "2020-01-24 08:00:00",
  "2020-01-23 14:00:00",
  "2020-01-23 12:00:00",
  "2020-01-23 09:00:00",
  "2020-01-22 09:00:00",
  "2020-01-22 13:00:00"
]

const groupedDates = _.groupBy(dates, date => date.split(' ')[0])

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