get selected dates from a range based on given days-CodePudding

I have a date range

Example Date Range:

const startDate = "2022-06-02";
const endDate = "2022-06-20";

I want to get those dates which comes on provided days array that falls between startDate & endDate

Example Array of Days:

["tuesday", "friday", "saturday"]

The expected result is :

Can anyone help me with this logic?

What I tried was so dirty, I put a loop on range of dates, and got the list of all dates, and then i put another loop to get name of day of each date, and then compared each day name in an array of days & pushed that date to new array

Here is the code (Which works perfectly fine) but I need better solution:

function getDaysArray(start, end) {
        
    for(var arr=[],dt=new Date(start); dt<=new Date(end); dt.setDate(dt.getDate() 1)){
        
        arr.push(helperClass.getDateTime(new Date(dt)).date);
    }
    
    return arr;
}

function getDayName (dateStr, locale){

    var date = new Date(dateStr);

    return date.toLocaleDateString(locale, { weekday: 'long' });        
}

var days = ["tuesday", "friday", "saturday"];

var getAllDates = getDaysArray("2022-06-02", "2022-06-20");
var getDates = [];
for(var i = 0; i < getAllDates.length; i  ){

    if(days.includes(getDayName(getAllDates[i]).toLowerCase())){

        getDates.push(getAllDates[i])
    }
}

CodePudding user response：

If you can use an external library, the date-fns library provides some helpers for this:

parse - Return the date parsed from string using the given format string.
eachDayOfInterval - Return the array of dates within the specified time interval.
getDay - Get the day of the week of the given date.
or is* helpers - e.g. isSunday, isMonday, etc.

So if you parse your start and end dates, get a full interval range, then filter it against the days, you'll have your list.

import("https://unpkg.com/[email protected]/esm/index.js").then(({ eachDayOfInterval, getDay, parse }) => {
    const startDate = parse("2022-06-02", "yyyy-MM-dd", new Date());
    const endDate = parse("2022-06-20", "yyyy-MM-dd", new Date());
    const daysOfWeek = ["sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday"];

    // Here is your list
    const daysToFilterFor = ["tuesday", "friday", "saturday"];
    const daysToFilterForIndex = daysToFilterFor.map((day) => daysOfWeek.indexOf(day));

    const range = eachDayOfInterval({
        start: startDate,
        end: endDate,
    }).filter((day) => daysToFilterForIndex.includes(getDay(day)));

    console.log(range);
});

CodePudding user response：

Details are commented in example

// Array of days to filter
const daysOff = ["Tuesday", "Friday", "Saturday"];

/**
 * @desc Determine the specific dates of days that match a given array
 * of weekdays within the range of two given dates.
 * @param {string<date>} start - The first date of the range
 * @param {string<date>} end - The last date of the range
 * @param {array<string>} weekdays - The list of days used to find the dates
 * @return {array<date>} An array of dates that correspond to weekdays
 */
function dateRanger(start, end, weekdays) {

  // Convert dates into timestamps {number}
  const A = Date.parse(start);
  const Z = Date.parse(end);

  // Seconds in a day
  const day = 86400000;
  // Determine number of days the range spans
  const total = Math.floor(((Z - A) / day)   1);
  // Object that stores format settings for .toLocaleDateString()
  const options = {
    weekday: 'long',
    year: 'numeric',
    month: 'numeric',
    day: 'numeric'
  };

  /*
  - Instantiate an Array with room to fit the range of dates
  - On each iteration instantiate a date based on the first date then format 
    it and add it's weekday using .toLocaleDateString() 
  - Return date string as an array of pairs using .split()
  */
  const range = [...new Array(total)].map(
    (_, i) => new Date(A   (day * i))
    .toLocaleDateString('en-US', options)
    .split(', ')
  );

  /*
  - .flatMap() the first level of range to access the array of pairs
  - On each iteration compare the first value of each pair (sub[0]) with the 
    given array (weekdays).
  - If there's a match, return the second value (sub[1]) of each pair 
  - Otherwise return an empty array that gets flattened to zilch.
  */
  return range.flatMap(
    sub => weekdays.flatMap(
      day => day === sub[0] ?
      sub[1] : []
    )
  );
}

console.log(dateRanger('6-4-2022', '6-20-2022', daysOff));

CodePudding user response：

I know this may be not the best way to do it, but here how I did it

let days = { monday: 0, tuesday: 1, wednesday: 2, thursday: 3, friday: 4, saturday: 5, sunday: 6 };
const startDate = "2022-06-02";
const endDate = "2022-06-20";
function daysindates(arr) {
    let stdate = startDate.substr(-2);
    let endate = endDate.substr(-2);
    let myarr = [],
        result = [],
        finalresult = [];
    for (y of arr) {
        for (let i = parseInt(stdate)   days[y]; i <= parseInt(endate); i  = 7) {
            result.push(i);
        }
    }
    finalresult = result.map((item) => {
        return "2022-06-"   item;
    });
    console.log(finalresult);
}

daysindates(["monday", "tuesday"]);