JS for-loop to get date difference in every array

Question

I am trying to sum up each member's total absent days.

Let's have only two members: A and B. A had left two times for different reasons, she went holiday off for 3 days and some other reason for 2 days. B had been hospitalized for 8 days, went vacation for 4 days.

So, here is the code I did my best.

*The dates I wrote is for example. Date values will be posted by JS onclick. No need of toString or something else.

var member = [{
  name : "A",
  absent : [{
    reason : "Leave",
    start_date : "2020-02-01",
    end_date : "2020-02-03"
  },{
    reason : "etc",
    start_date : "2020-02-15",
    end_date : "2020-02-16"
  }
  ]
},{
  name : "B",
  absent : [{
    reason : "Hospitalized",
    start_date : "2020-02-03",
    end_date : "2020-02-10"
  },{
    reason : "Leave",
    start_date : "2020-02-10",
    end_date : "2020-02-13"
  }
  ]
}]

var countAbsentDays = function(){
  var countDays_start = member[0].absent[0].start_date;
  var countDays_end = member[0].absent[0].end_date;
  var diff = (new Date(countDays_end)) - (new Date(countDays_start));
  var count = diff/(1000 * 60 * 60 * 24);
  
  return count;
};

console.log(countabsentDays());

To collect each member's total absent days, I need to develop the code below using for-loop.

 var countDays_start = member[0].absent[0].start_date;

Guess, the index number I put 0 could be replaced with variable. But I can't picture how this function runs all over absent array and its element absent.start_date and absent.end_date.

Anybody help?

user120242 · Accepted Answer · 2020-04-18 14:32:23Z

You can use map to transform an array, and reduce to accumulate the array elements into a value.

    var member = [{
      name : "A",
      absent : [{
        reason : "Leave",
        start_date : "2020-02-01",
        end_date : "2020-02-03"
      },{
        reason : "etc",
        start_date : "2020-02-15",
        end_date : "2020-02-16"
      }
      ]
    },{
      name : "B",
      absent : [{
        reason : "Hospitalized",
        start_date : "2020-02-03",
        end_date : "2020-02-10"
      },{
        reason : "Leave",
        start_date : "2020-02-10",
        end_date : "2020-02-13"
      }
      ]
    }]

    var countAbsentDays = function(){
      return member.map( m => // map every element of member array to object { [m.name]: (reduced value of absent array) }
          ({
             [m.name]: 
                m.absent.reduce(
                    (acc, x) => 
                      acc + dateDiff(x.end_date, x.start_date)
                , 0 )  // accumulator + dateDiff result returned for every element
           })
      );
      function dateDiff(end, start) {
        var countDays_start = start;
        var countDays_end = end;
        var diff = (new Date(countDays_end)) - (new Date(countDays_start));
        var count = diff/(1000 * 60 * 60 * 24);

        return count;
      }
    };

    console.log(countAbsentDays());

Collectives™ on Stack Overflow

JS for-loop to get date difference in every array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related