How can I find and display next and previous Wednesday in javascript?

October 6, 2022

I want to find date of previous Wednesday in ‘YYYY-MM-DD" format given date string = ‘YYYY-MM-DD". Exclusive of today being Wednesday.

I also want to find date of next Wednesday in ‘YYYY-MM-DD" format given date string = ‘YYYY-MM-DD". Exclusive of today being Wednesday.

date_Event = '2022-10-05';

function prevWed() {
    const str_1 = date_Event;
    const [year, month, day] = str_1.split('-');
    const date_1 = new Date(+year, month - 1, +(day - 7));
    alert(date_1.toISOString().split('T')[0]); // 2022-09-21 FINE!
}

function nextWed() {
    const str_2 = date_Event;
    const [year, month, day] = str_2.split('-');

    // this is OK, as long as today = "3" but I need the next Wed. regardless of today
    const date_2 = new Date(+year, month - 1, +(day + 7));
    alert(date_2.toISOString().split('T')[0]); // 2023-06-14  COMPLETELY WRONG!
}

prevWed();
nextWed();

>Solution :

The problem is +(day + 7). The day is a string, let’s say its "05", while ("05" + 7) resolves into "057" and +"057" is 57; You need to convert the day into number first and then do the addition without the parenthesis: +day + 7

date_Event = '2022-10-05';

function prevWed() {
    const str_1 = date_Event;
    const [year, month, day] = str_1.split('-');
    const date_1 = new Date(+year, month - 1, +day - 7);
    alert(date_1.toISOString().split('T')[0]); // 2022-09-21 FINE!
}

function nextWed() {
    const str_2 = date_Event;
    const [year, month, day] = str_2.split('-');

    // this is OK, as long as today = "3" but I need the next Wed. regardless of today
    const date_2 = new Date(+year, month - 1, +day + 7);
    alert(date_2.toISOString().split('T')[0]); // 2023-06-14  COMPLETELY WRONG!
}

prevWed();
nextWed();