如何在Javascript中将第一个工作日设置为星期一？

Question

I built an app totally based in dates. Now the client really wants to make Monday as the 1st day of week and I've plenty of calendar views, diary view, log views, calculations, etc based in dates and always considering Sunday as first day of week because it's Javascript default. It's the day zero when you call the GetDay() function of the Date object.

Is there something I can do to set the 1st day of week as Monday ?

ty !

Answer 1

If you want monday as first day you can do this:

const dayIndex = defaultDayIndex === 0 ? 6 : defaultDayIndex-1;

const myDate = new Date('2021-12-07');

const defaultDayIndex = myDate.getDay();
// make monday first day of the week and sunday the last day
// monday will be index 0, and sunday will be index 6
const dayIndex = defaultDayIndex === 0 ? 6 : defaultDayIndex-1;

Answer 2

const weekMap = {
    1: 0, // → monday
    2: 1, // → tuesday
    3: 2, // → wednesday
    4: 3, // → thursday
    5: 4, // → friday
    6: 5, // → saturday
    0: 6, // → sunday
};

console.log(weekMap[(new Date()).getDay()]);