I am trying to convert the number of days since Jan 01 1970 to JavaScript Date.
Here is the code snippet.
new Date(864e5 * parseInt(data[i].d));
//here data[i].d contains number of days.
I checked all the data by this.
console.log(typeof(data[i].d), data[i].d);
//prints
number 17674
but sometimes it unable to convert it into date.
Invalid Date {}
while for
number 17858
//outputs.
Fri Aug 17 2018 05:00:00 GMT+0500 (Pakistan Standard Time)
Thanks for your time.
You just have to add the number of days times the milliseconds in a day, like so:
var originalDay = new Date(864e5)
console.log(originalDay) //Thu Jan 01 1970 19:00:00 GMT-0500 (Eastern Standard Time)
var numOfDays = 7
var daysSince = new Date(864e5 + parseInt(numOfDays * 864e5))
console.log(daysSince) //Thu Jan 08 1970 19:00:00 GMT-0500 (Eastern Standard Time) --7 days later
To make this work for you, you would just have to replace that numOfDays with the values in your array.
Related
Having this input: Wed Feb 03 2021 00:00:00 GMT+0200 (Eastern European Standard Time), is there a way to format it as YYYY-MM-DD, to it will become 2021-02-03?
Try this:
const date = moment(new Date('Wed Feb 03 2021 00:00:00 GMT+0200 (Eastern European Standard Time)')).format('YYYY-MM-DD');
console.log(date);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js" integrity="sha512-qTXRIMyZIFb8iQcfjXWCO8+M5Tbc38Qi5WzdPOYZHIlZpzBHG3L3by84BBBOiRGiEb7KKtAOAs5qYdUiZiQNNQ==" crossorigin="anonymous"></script>
Parsing a timestamp to a date to reformat it may well produce incorrect results if the timestamp includes an offset or timezone. Given "Wed Feb 03 2021 00:00:00 GMT+0200 (Eastern European Standard Time)", for a user with an offset of +1 or less the date will be 2 Feb, not 3 Feb.
The most reliable method is to reformat the string, e.g.
let timestamp = "Wed Feb 03 2021 00:00:00 GMT+0200 (Eastern European Standard Time)";
let months = [,'Jan','Feb','Mar','Apr','May','Jun',
'Jul','Aug','Sep','Oct','Nov','Dec'];
let pad = n=>('0'+n).slice(-2);
let p = timestamp.split(' ');
console.log(`${p[3]}-${pad(months.indexOf(p[1]))}-${p[2]}`);
I want to create an array that contains unique months (August 2015, September 2015 etc.). For this I defined the following function that takes an object with timestamps as keys:
export function getUniqueMonths(exps) {
//1. get all keys from expenditures
const days = Object.keys(exps)
//2. convert key strings to timestamps
const daysInt = days.map((day) => (new Date(parseInt(day))))
//3. return only the "date portion" of the timestamp
const datePortion = daysInt.map((day) => (new Date(day.toDateString()) ))
//4. set each datePortion to 1st of month
const firstOfMonth = datePortion.map((day) => new Date(day.getFullYear(), day.getMonth(), 1) )
//5. keep only unique firstOfMonths
const uniqMonths = [...(new Set(firstOfMonth))]
return uniqMonths
}
However, this function gives me an array like this:
[Sat Aug 01 2015 00:00:00 GMT+0300 (Eastern European Summer Time), Sat Aug 01 2015 00:00:00 GMT+0300 (Eastern European Summer Time), Tue Sep 01 2015 00:00:00 GMT+0300 (Eastern European Summer Time), Sat Aug 01 2015 00:00:00 GMT+0300 (Eastern European Summer Time), Sat Aug 01 2015 00:00:00 GMT+0300 (Eastern European Summer Time), ...]
I thought getting the date portion of the timestamp (step 3) and setting all dates to first of month (step 4) would do the trick. But I still have duplicates in my array.
What am I missing?
I think you might be overengineering things :) Something like
function getUniqueMonths(exps) {
const uniqueMonths = new Set();
Object.keys(exps).forEach((timestamp) => {
const date = new Date(parseInt(timestamp)); // expected to be milliseconds since 1/1/1970
uniqueMonths.add(`${date.getFullYear()}-${date.getMonth()}`);
});
return uniqueMonths;
}
should get you a Set of unique months in the form of ['2017-12', '2018-0', ...] (zero-based months as is the JavaScript standard).
If you need Date objects, those are trivial to "rehydrate".
Two Date objects are not the same object, even if they contain the same timestamp.
Instead, try:
//3. keep the year-month portion of the date
const yearMonths = daysInt.map(day => day.getFullYear()+"-"+day.getMonth());
Then you can skip 4 and just get the unique year-months from there. These will be returned as "2015-7" for August 2015, for example.
I want to convert date to millisecond as per follow I converted.
var d = new Date(1454911465467) \\ output : Mon Feb 08 2016 11:34:25 GMT+0530 (IST)
Now I want to convert using output to millisecond.
var d = new Date('Mon Feb 08 2016 11:34:25 GMT+0530 (IST)').getTime() \\output : 1454911465000
Expected output : 1454911465467
Is their any way to convert these type of millisecond?
Milliseconds are not specified in 'Mon Feb 08 2016 11:34:25 GMT+0530 (IST)'. The date precision here is down to seconds. Hence 467 milliseconds are missed in the second result.
You can check e.g.
var originalDate = new Date(1454911465467);
var clonnedDate = new Date(originalDate.getFullYear(), originalDate.getMonth(), originalDate.getDate(), originalDate.getHours(), originalDate.getMinutes(), originalDate.getSeconds(), originalDate.getMilliseconds());
document.write(clonnedDate.getTime());
I have some interesting problem and can't find the solution. Look at this:
var d1 = new Date("07 31 2014");
document.write(d1);
document.write('<br />');
var d2 = new Date(1406746800 * 1000);
document.write(d2);
when I run this script I get this result:
Thu Jul 31 2014 00:00:00 GMT+0500 (UZT)
Thu Jul 31 2014 00:00:00 GMT+0500 (UZT)
then after I changed my time zone I get this result:
Thu Jul 31 2014 00:00:00 GMT-0800 (AKDT)
Wed Jul 30 2014 11:00:00 GMT-0800 (AKDT)
as you can see the second result is Jul 30, but first result is Jul 31. I think they must both be equal to 31 Jul. I know this problem depends on the timezone but is there a solution?
So the constructor parameter is:
an Integer value representing the number of milliseconds since 1
January 1970 00:00:00 UTC
So given your integer value, that represents (for me, in BST):
Wed Jul 30 2014 20:00:00 GMT+0100
Which is
Wed Jul 30 2014 19:00:00 UTC
And your timezone is GMT-8, so thats the above -8 which gives:
Wed Jul 30 2014 11:00:00 GMT-0800 AKDT
The date string constructor constructs the date in your local timezone. You can see what the value should be by doing this:
new Date("07 31 2014").getTime() / 1000
Which returns 1406761200, not 1406746800
I have a date in the format 14-Feb-2011, but I want to convert it into the format Mon Feb 14 10:13:50 UTC+0530 2011. How Can I achieve this?
Using new Date(Date.UTC(year, month, day, hour, minute, second)) you can create a Date-object from a specific UTC time.
I tried this code and it returned proper date (In Indian Locale)
var d=Date.parse("14,Feb,2011");
document.write(new Date(d));
Output:
Mon Feb 14 2011 00:00:00 GMT+0530 (India Standard Time) .
Here's an example of converting between different time zones.
<html>
<body>
<script type="text/javascript">
//Set you offset here like +5.5 for IST
var offsetIST = 5.5;
//Set you offset here like -8 for PST
var offsetPST = -8;
//Create a new date from the Given string
var d=new Date(Date.parse("14,Feb,2011"));
//To convert to UTC datetime by subtracting the current Timezone offset
var utcdate = new Date(d.getTime() + (d.getTimezoneOffset()*60000));
//Then cinver the UTS date to the required time zone offset like back to 5.5 for IST
var istdate = new Date(utcdate.getTime() - ((-offsetIST*60)*60000));
//Then cinver the UTS date to the required time zone offset like back to -8 for PST (Canada US)
var pstdate= new Date(utcdate.getTime() - ((-offsetPST*60)*60000));
document.write(d);
document.write("<br/>");
document.write(utcdate);
document.write("<br/>");
document.write(istdate);
document.write("<br/>");
document.write(pstdate);
</script>
</body>
</html>
Output:
Mon Feb 14 2011 00:00:00 GMT+0530 (India Standard Time)
Sun Feb 13 2011 18:30:00 GMT+0530 (India Standard Time)
Mon Feb 14 2011 00:00:00 GMT+0530 (India Standard Time)
Sun Feb 13 2011 10:30:00 GMT+0530 (India Standard Time)
Its writing IST every where because new Date() always show date as local timezone (which is IST for me) but above datetime are actually Original, UTC, IST, PST respectively.
var d = new Date("14-Feb-2011");
this will give an output of
Mon Feb 14 2011 00:00:00 GMT-0500 (Eastern Standard Time)