Develop Reference

Is there a way to swap dayweek and date, when formatting a date in JavaScript?

I've formatted my date like below, but I would like the weekday to go after the DD/MM/YYYY. Is this possible?
Current output: Friday, 16/06/2023, 12:00
Desired output: 16/06/2023, Friday, 12:00
const options = {
weekday: 'long',
year: 'numeric',
month: 'numeric',
day: 'numeric',
hour: 'numeric',
minute: 'numeric',
};
const dt = new Date('2023-06-16T12:00:00Z').toLocaleDateString('en-GB', options)
console.log(dt)

You can do by custom code format of required output.
In your case to acheive desired result this code help you.
const options = {
year: 'numeric',
month: 'numeric',
day: 'numeric',
weekday: 'long',
hour: 'numeric',
minute: 'numeric',
};
const dt = new Date('2023-06-16T12:00:00Z');
const formattedDate = `${dt.toLocaleDateString('en-GB', {
year: 'numeric',
month: 'numeric',
day: 'numeric',
})}, ${dt.toLocaleDateString('en-GB', {
weekday: 'long',
})}, ${dt.toLocaleTimeString('en-GB', {
hour: 'numeric',
minute: 'numeric',
})}`;
console.log(formattedDate);

get new Date() in other timezone in full text string format

I need to get Thailand timezone in this format: Thu Nov 10 2022 14:08:37 GMT+0800 (Malaysia Time). I have tried new Date().toLocaleString("en-US", {timeZone: "Asia/Bangkok"}) but didn't get the correct format I want, probably because of the .toLocaleString(). Is there a simple way to do it?

As deceze suggests, you can use Intl.DateTimeFormat with suitable options to get the values you want. Then you can use formatToParts to reorganise them as you wish, e.g. to replicate the format of Date.prototype.toString for any timezone, you can use:
// Return timestamp in same format as Date.prototype.toString
// in designated timezone (IANA representative location)
function toTimezone(tz, date = new Date()) {
// Get parts except timezone name
let opts = {
year: 'numeric',
month: 'short',
day: '2-digit',
weekday: 'short',
hour: '2-digit',
minute: '2-digit',
second: '2-digit',
timeZone: tz,
timeZoneName: 'shortOffset',
hour12: false
}
// To get full timezone name
let opts2 = {
hour: 'numeric',
timeZone: tz,
timeZoneName: 'long'
}
let toParts = opts => new Intl.DateTimeFormat('en', opts)
.formatToParts(date)
.reduce((acc, part) => {
acc[part.type] = part.value;
return acc;
}, Object.create(null));
let {year, month, day, weekday, hour, minute,
second, timeZoneName} = toParts(opts);
// Fix offset
let sign = /\+/.test(timeZoneName)? '+' : '-';
let [oH, oM] = timeZoneName.substr(4).split(':');
let offset = `GMT${sign}${oH.padStart(2, '0')}${oM || '00'}`;
// Get timezone name
timeZoneName = toParts(opts2).timeZoneName;
return `${weekday} ${month} ${day} ${year} ${hour}:${minute}:${second} ${offset} (${timeZoneName})`;
}
// Examples
['Australia/Adelaide',
'Asia/Bangkok',
'Asia/Kolkata',
'America/New_York',
'Pacific/Yap',
'Pacific/Pago_Pago'
].forEach(tz => console.log(toTimezone(tz)));
Support for some options like shortOffset may not be ubiquitous yet. A formatting library with timezone support is a simpler (and more reliable) option. :-)

You can configure the locale string formatter with a whole bunch of options:
console.log(new Date().toLocaleString('en-US', {
timeZone: 'Asia/Bangkok',
weekday: 'short',
year: 'numeric',
month: 'short',
day: 'numeric',
hour: 'numeric',
minute: 'numeric',
second: 'numeric',
timeZoneName: 'short',
hour12: false
}));
However, the exact format it will output will always be dependent on the locale used and the browser's understanding of how dates should be formatted for that locale. If you want more control over the exact formatting, you'll need to cobble it together yourself:
const date = new Date();
const time = date.toLocaleString('en-US', {
timeZone: 'Asia/Bangkok',
hour: 'numeric',
minute: 'numeric',
second: 'numeric',
timeZoneName: 'short',
hour12: false
});
const weekday = date.toLocaleString('en-US', {
timeZone: 'Asia/Bangkok',
weekday: 'short'
});
console.log(`${weekday} ${date.getFullYear()} ... ${time}`);
If that seems too complicated, use some 3rd party library like Luxon, which can simplify that a bit.

Js Date - Unix Time Stamp wrong result

Hi I have generated a Unix Time Stamp with an online generator and I choose that Date:
01/12/2020 # 9:30pm (UTC)
Which gave me result: 1578864600
I want to display it now in my react app: (date is my result above)
const timestamp = new Date().setMilliseconds(date);
const formattedDate = new Intl.DateTimeFormat('pl-PL', {
year: 'numeric',
month: 'numeric',
day: 'numeric',
weekday: 'long',
hour: 'numeric',
minute: 'numeric',
}).format(timestamp);
But in my react app I am getting that wrong Date:
Tuesday, 14.01.2020, 17:07
Why it is calculating it wrong??

Why does the date format function return incorrect answer?

I need to format date. I use function Intl.DateTimeFormat but I don't understand why it does not format correctly fTime
Example:
const date = new Date()
console.log('Date:', date)
const dateOptions = { year: 'numeric', month: 'numeric', day: 'numeric' }
const timeOptions = { hour: 'numeric', minute: 'numeric', second: 'numeric', hour12: false }
const fDate = new Intl.DateTimeFormat(dateOptions).format(date)
const fTime = new Intl.DateTimeFormat(timeOptions).format(date)
console.log('fDate:', fDate)
console.log('fTime:', fTime)
I'm expecting to get an answer like this ( in my case such 20:10:25 )

You're passing the options to the locales parameter. Even if locales is optional, it just means you don't need to supply a value for it; it doesn't mean you can try to skip it. If you don't want to supply a value for locales but for options, pass undefined instead:
const date = new Date()
console.log('Date:', date)
const dateOptions = { year: 'numeric', month: 'numeric', day: 'numeric' }
const timeOptions = { hour: 'numeric', minute: 'numeric', second: 'numeric', hour12: false }
const fDate = new Intl.DateTimeFormat(undefined, dateOptions).format(date)
const fTime = new Intl.DateTimeFormat(undefined, timeOptions).format(date)
console.log('fDate:', fDate)
console.log('fTime:', fTime)

date.toLocaleString(options) does not work javascript

I am quite new to JS and need some help.
I want to format date with the help of toLocaleString(). According to standards first argument 'locales' can be omitted. My code looks like:
let myDate = new Date(2014, 0, 30)
let options = {
year: '2-digit',
month: '2-digit',
day: '2-digit'
};
let formattedDate = myDate.toLocaleString(options);
console.log(formattedDate);

While you can skip the first argument, without supplying something for it in your case, you won't get the options argument to give you the results you want.
Here are a few versions of working code:
let date = new Date(2014, 0, 30);
let options = {
year: '2-digit',
month: '2-digit',
day: '2-digit'
};
console.log(date.toLocaleString('en-us', options));
console.log(date.toLocaleString(undefined, options));
console.log(date.toLocaleString(options));
options.timeZone = 'UTC';
options.timeZoneName = 'short';
console.log(date.toLocaleString('en-US', options));
// sometimes even the US needs 24-hour time
console.log(date.toLocaleString('en-US', { hour12: false }));

The first argument to toLocaleString is not optional, but you can pass undefined to it.
let date = new Date(2014, 0, 30)
let options = {
year: '2-digit',
month: '2-digit',
day: '2-digit'
};
let formattedDate = date.toLocaleString(undefined, options);
console.log(formattedDate);

You should use the options as second parameter:
let date = new Date(2014, 2, 2)
let options = {
year: '2-digit',
month: '2-digit',
day: '2-digit'
};
let formattedDate = date.toLocaleString(undefined, options);