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Gives back the week start date and end date, provided a week number, year, and starting day (Using moment)
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| // http://en.wikipedia.org/wiki/ISO_8601#Week_dates | |
| // http://stackoverflow.com/questions/662379/calculate-date-from-week-number | |
| getDatesFromWeek: function (week, year, startOfWeekDay) { | |
| if (startOfWeekDay == undefined || startOfWeekDay == null) | |
| startOfWeekDay = 0; // Default StartOfWeek to Sunday if not provided | |
| // ISO 8601 defines the week where first Thursday of the year is has Week 1 | |
| // create a variable holding the position of thursday in the week | |
| var thursday = 4; | |
| // First set a basis of january one for the current year | |
| var januaryOne = new Date(Date.UTC(year, 0, 1)); | |
| // ISO 8601 defines the week where first Thursday of the year is has Week 1 | |
| // Calculate the offset of days between the first thursday and January 1 | |
| var daysOffset = thursday - januaryOne.getDay(); | |
| // Then get the first thursday date | |
| var firstThursday = januaryOne; | |
| firstThursday.setDate(firstThursday.getDate() + daysOffset); | |
| // Later on we will multiply the week we ask for | |
| // by 7 days to add to the date, so lower week to 0 if we're asking for first week | |
| var firstWeek = moment(firstThursday).isoWeek(); | |
| var weekNumber = week; | |
| if (firstWeek <= 1) { | |
| weekNumber -= 1; | |
| } | |
| // Match week that was asked for | |
| // Add as much days as needed depending on the week we're asking for | |
| var startDate = firstThursday; | |
| startDate.setDate(startDate.getDate() + (weekNumber * 7)); | |
| // Start Date right now is set to thursday, match the start of week day that was asked for by adding / removing days | |
| var startDateDayOffset; | |
| if (startOfWeekDay == 0) { | |
| // If specific start of day is Sunday, add 3 days | |
| startDateDayOffset = 3; | |
| } else { | |
| // Otherwise the offset calculation is simple | |
| startDateDayOffset = startOfWeekDay - thursday; | |
| } | |
| // Apply the calculated offset to get the start date for the provided week given a specific starting day | |
| startDate.setDate(startDate.getDate() + startDateDayOffset); | |
| // End Date is startDate + 6 | |
| var endDate = new Date(Date.UTC(startDate.getFullYear(), startDate.getMonth(), startDate.getDate() + 6)); | |
| return { startDate: startDate, endDate: endDate, week: week, year: year }; | |
| }, |
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