Sort String of Date & Time within array of object

Question

Given:

[{
    date: "2020-12-23",
    session: "14:00:00-15:00:00"
}, {
    date: "2020-12-23",
    session: "10:00:00-12:00:00"
},{
    date: "2020-12-23",
    session: "12:00:00-14:00:00"
},{
    date: "2020-12-22",
    session: "14:00:00-15:00:00"
}]

How to sort by date & session? because both of them are string, especially session was range of time

Answer 1

Sort requires a function that compares two elements of the array and returns a number: positive, negative or a zero.

Now, since we have to handle date and time, we pick date from each component and pick the beginning of the session timestamp by splitting and fetching the first half of the session string. We concatenate the date and time to make it easy parse into milliseconds. The milliseconds can now be used in our comparator to compare the session start time.

 const v = [{ date: "2020-12-23", session: "14:00:00-15:00:00" }, { date: "2020-12-23", session: "10:00:00-12:00:00" },{ date: "2020-12-23", session: "12:00:00-14:00:00" },{ date: "2020-12-22", session: "14:00:00-15:00:00" }]; const parser = ({date, session}) => Date.parse(`${date}T${session.split('-')[0]}`) v.sort((a, b) => parser(a) - parser(b)) console.log(v)

returns

[
  {
    "date": "2020-12-22",
    "session": "14:00:00-15:00:00"
  },
  {
    "date": "2020-12-23",
    "session": "10:00:00-12:00:00"
  },
  {
    "date": "2020-12-23",
    "session": "12:00:00-14:00:00"
  },
  {
    "date": "2020-12-23",
    "session": "14:00:00-15:00:00"
  }
]

Answer 2

This can be accomplished using a custom comparison function. Concatenate the strings and use the built in string comparison method.

exams.sort( 
    (a,b) => (a.date+a.session).localeCompare(b.date+b.session)
)