Difference of days between two dates in React.JS using moment

Question

I made a function which calculates difference between two dates, but i dont know how to take(?) data to it using inputs. I also tried to return diffInDays; and instead of that use this.setState({ diffInDays: diffInDays }) . I've tried many combinations but none of them gave me the right result.

calculate(dateFrom, dateTo) {
    if (!dateFrom || !dateTo) {
       return null;
    }
    const arrival = moment(dateFrom);
    const departure = moment(dateTo);
    if (arrival.isAfter(departure)) {
       return null;
    }
      const diffInDays = departure
      .endOf('day')
      .diff(arrival.startOf('day'), 'days');
    
      return diffInDays;
}

those are the inputs I created:

• this one is for the beginning

<div className="form-group">
  <label htmlFor="dateFrom">Date From: </label>
  <input
    type="date"
    className="form-control"
    id="dateFrom"
    onChange={this.onChangeDateFrom}
    value={this.state.dateFrom}
    name="dateFrom"
   />
</div>

• and this one is for the end

<div className="form-group">
    <label htmlFor="dateTo">Date to: </label>
    <input
    type="date"
    className="form-control"
    id="dateTo"
    onChange={this.onChangeDateTo}
    value={this.state.dateTo}
    name="dateTo"
    />
</div>

• and this is the one where I want to see the difference

<div className="form-group">
   <label htmlFor="daysDiff">Days Difference: </label>
   <input
   type="number"
   className="form-control"
   id="daysDiff"
   required
   value={this.state.daysDiff}
   name="daysDiff"
   readOnly
   />
</div>

Picking the dates works fine. They also save in the MongoDB, the problem appears only with the difference of days.

Answer 1

You should use departure.diff(arrival) and for getting only day difference departure.diff(arrival,'days')