Need array of dates to go from Mon-Sun-CodePudding

I have a function that gets all days of any input dates's week. I use this later on to render a calendar.

However, the dates go from Sunday-Saturday when I want them going from Monday-Sunday. I feel like the would be an easy change but I can't seem to figure it out.

const createNewWeek = (startDate) => {
  const newDates = Array.from(Array(7).keys()).map((idx) => {
    const d = new Date(startDate);
    d.setDate(d.getDate() - d.getDay()   idx);
    return d;
  })
  return newDates
}
console.log(createNewWeek(new Date()))

CodePudding user response：

Find previous monday for a given Date and create an array with 7 subsequent dates starting with the found monday.

Fork this stackblitz project to play with this code.

const getMonday = d => new Date(d - (d.getDay()-1) * 864e5);
  const dow = d => [`su`, `mo`, `tu`, `we`, `th`, `fr`, `sa`]
    .find( (_, i) => d === i);
  const createNewWeek = maybeMonday => [...Array(6)]
    .reduce( (acc, d, i) => 
      [...acc, new Date( acc[0]   (i 1) * 864e5)], 
      [getMonday(new Date(maybeMonday.toUTCString()))] )
    .map( d => `${dow(d.getDay())} ${d.toLocaleDateString()}` );
  const now = new Date();
  const then = new Date(1927,2,15)

  console.log(`This week from ${now.toLocaleDateString()}\n`, 
    createNewWeek(now));
  console.log(`Another week from ${then.toLocaleDateString()}\n`, 
    createNewWeek(then));
/*
  notes:
  - 864e5 is the number of milliseconds of one day
  - uses utc date to prevent time zone surprises
  - The reducer is sufficient to create the array of dates
    (so map and dow function are only for this snippet). 
*/

.as-console-wrapper {
    max-height: 100% !important;
}

CodePudding user response：

As Kooilnc says, get the previous Monday and build an array of 7 dates. The following is an example using basic JS that is likely much more efficient than generating lots of unnecessary arrays purely for the sake of avoiding a boring old for loop.

function getMonToSun(date = new Date()) {
  // Result array
  let week = [];
  // Prior Monday
  let mon = new Date(date.getFullYear(), date.getMonth(),
                     date.getDate() - (date.getDay() || 7)   1);
  // Build array of 7 dates from Monday
  for (let i=0; i<7; i  ) {
    week.push(new Date(mon.getFullYear(), mon.getMonth(), mon.getDate()   i));
  }
  return week;
}

// Current week
console.log(getMonToSun().join('\n'));
// Week of 1 Jan 2000
console.log(getMonToSun(new Date(2000,0,1)).join('\n'));