Question 294321 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Move timestamp to the next Monday 10:01 AM

I’ve been battling ChatGPT for hours now and can’t get satisfied with this simple algorithm in TypeScript.

function computeUpcomingNotificationTimestamp(
    currentTimestamp: number = Date.now(),
    day: number = 1,
    hours: number = 10,
    minutes: number = 1
): number {
    const currentTimeInMilliseconds: number =
        date.getHours() * 60 * 60 * 1000 // Hours to milliseconds
       +date.getMinutes() * 60 * 1000    // Minutes to milliseconds
       +date.getSeconds() * 1000         // Seconds to milliseconds
       +date.getMilliseconds();          // Milliseconds

    const timeOfNotification: number =
        hours * 60 * 60 * 1000 // Hours to milliseconds
       +minutes * 60 * 1000;   // Minutes to milliseconds

    if (date.getDay() === day) {
        if (currentTimeInMilliseconds >= timeOfNotification) {
            date.setDate(date.getDate() + 7);
        }
    } else {
        while (date.getDay() !== day) {
            date.setDate(date.getDate() + 1);
        }
    }

    date.setHours(hours, minutes, 0, 0);

    return date.getTime();
}

This solution is (hopefully) correct and moves timestamp to the nearest Monday 10:01 AM. What I wish to achieve is a solution that has these properties.

Comprehensible for humans

  • it must be readily apparent, so transparent a CHILD should grasp it instantly and SWEAR it is correct. If it were a suspect domicile and you were a cop who have 10 seconds to persuade the judge to grant you a search warrant, you MUST be able to SWAY HIM!
  • No hacks, no bit-shifts, no Quake 3 arena stuff, nothing too clever
  • just something concisely elegant and vivid

Other important features

  • correct
  • good programming practises (no spaghetti code, complicated conditions, nested if-else)
  • functional, if it serves the purpose
  • pragmatic (if there is a library, just use it please)

This is the closest I got, but there must be a better way. I would be beholden to you, the community.

Update

The original solution wasn’t even correct! Here is the correct one. Can you make it shorter?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    You could try this.

    function crazyInefficient(
    currentTimestamp: number = Date.now(), 
    day: number = 1, 
    hours: number = 10, 
    minutes: number = 1
): number {
    const date: Date = new Date(currentTimestamp);        
    do {
        date.setTime(date.getTime() + 1);
    } while (date.getDay() !== day || date.getHours() !== hours || date.getMinutes() !== minutes || date.getSeconds() !== 0 || date.getMilliseconds() !== 0);

    return date.getTime();
}

  2. 0 
    function computeUpcomingNotificationTimestamp(currentTimestamp: number = Date.now(), day: number = 1, hours: number = 10, minutes: number = 1): number {
    const date: Date = new Date(currentTimestamp);

    if (!isValidTimestamp(currentTimestamp)) {
        console.error(`computeUpcomingNotificationTimestamp: currentTimestamp=${currentTimestamp} has invalid value`);
        return currentTimestamp; // highlighting won't be synchronized with notifications
    }

    if (date.getDay() === day) {
        if (date.getHours() * 60 + date.getMinutes() >= hours * 60 + minutes){
            date.setDate(date.getDate() + 7);
        }
    } else {
        while (date.getDay() !== day) {
            date.setDate(date.getDate() + 1);
        }
    }

    date.setHours(hours, minutes, 0, 0);

    return date.getTime();
}
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