Why do this function doesn't return a random time that's > from now?

Question

I'm trying to use following function (taken from an another answer) to get a random time that's > from now and within a hourly range.

I don't know exact value I need to put into startHour

My time is 4 PM EST US and I put 16 there and 5 to the hourRange but it gives me values that's less than that.

function randomTime(rangeOfDays = 0, startHour, hourRange){
    var today = new Date(Date.now());
    return new Date(today.getYear()+1900,today.getMonth(), today.getDate()+Math.random() *rangeOfDays, Math.random()*hourRange + startHour, Math.random()*60)
}

Link to that answer, Answer

Think in ticks only. In other words just add ticks to the current ticks value. — Bibberty, Feb 03 '21 at 21:16
@trincot Not mine. It's stated in the question that I've taken it from an another SO answer. — jeffbRTC, Feb 03 '21 at 21:17
So why don't you just write code that you need? Maybe provide some concrete examples of input and expected output, and then we can maybe help you provide a function for it. — trincot, Feb 03 '21 at 21:17
Please at least link to the other answer, as required by the CC-by-SA-4.0 license... — Heretic Monkey, Feb 03 '21 at 21:18
Tricky, but I think its important to understand this type of exercise really requires `ticks` within a certain scale must be added. — Bibberty, Feb 03 '21 at 21:28
Under the answer there is a comment, pointing out the mistake in this code: `this.getMonth()` should be `this.getMonth() + 1`. — Jonas Wilms, Feb 03 '21 at 22:22

score 2 · Accepted Answer · answered Feb 03 '21 at 21:26

2

Here this deals with the problem by working with Ticks only. Which is easier to manage.

const getRandomTime = (offsetHour = 0, rangeInHours = 2) => {
  const curTicks = Date.now() + 0 * (offsetHour*60*60*1000);
  const addTicks = (Math.random()*rangeInHours)*60*60*1000;
  
  return new Date(curTicks + addTicks);

};

console.log((new Date()));
for(let i=0; i<10;i++) {
  console.log( getRandomTime(1, 2+i));
}

answered Feb 03 '21 at 21:26

Bibberty

4,670
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What exactly offsetHour do mean? – jeffbRTC Feb 03 '21 at 21:30
That allows you to say give me a random time starting at a minumum in X hours. e.g. `getRandomTime(24, 4)` will return a `Date` in a 4 hour range 24hrs from now. – Bibberty Feb 03 '21 at 21:31
Does it make sense. – Bibberty Feb 03 '21 at 21:35
I'm still puzzled of the 24 parameter and 4, feels like two ranges. – jeffbRTC Feb 03 '21 at 21:40
Give me some time to think. – jeffbRTC Feb 03 '21 at 21:40
Jeff, the first param just allows you to get a random time for a future date. Passing `0` is effectively a random time from `now()` – Bibberty Feb 03 '21 at 21:42
How to get a time within 9 and 5 range because yours gives me times around mid night.? – jeffbRTC Apr 11 '21 at 12:35
Actually, I think your code has a bug. Even if I specify range of two hours, it gives me time values that exceed that limit such as mid night. – jeffbRTC Apr 11 '21 at 13:51

Why do this function doesn't return a random time that's > from now?

1 Answers1

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