Fix - getDate() returns the wrong date in JavaScript


Borislav Hadzhiev

Sun Jan 23 20223 min read

Fix - getDate() returns the wrong date in JavaScript #

The getDate() method might return a wrong date when passing a string to the Date() constructor, e.g. new Date(dateString). How date strings are parsed is implementation dependent and might vary between browsers.

For consistent results when creating a Date object, pass multiple, comma-separated values for the year, month, day, hour, minutes and seconds to the Date() constructor.

// 👇️ formatted as YYYY-MM-DD hh:mm:ss const dateStr = '2022-09-24 07:30:24'; const [dateComponents, timeComponents] = dateStr.split(' '); console.log(dateComponents); // 👉️ 2022-09-22 console.log(timeComponents); // 👉️ 07:30:24 const [year, month, day] = dateComponents.split('-'); const [hours, minutes, seconds] = timeComponents.split(':'); // ✅ Create Date using multiple, comma-separated parameters const date = new Date(+year, +month - 1, +day, +hours, +minutes, +seconds); console.log(date); // 👉️ Sat Sep 24 2022 07:30:24 console.log(date.getDate()); // 👉️ 24

How the Date() constructor interprets the passed in Date() strings can vary between implementations.

This could be the cause of the getDate method returning a wrong date.

A common issue when creating dates with date strings is that if you live in an area that's behind GMT, you might get a date of the previous day.

If you create a date with a date string (without specifying time), you get a date set in UTC.

For example, if you create a new Date('2022-09-24'), you end up creating a date for the 24th of September 2022, 12AM UTC.

But if you live in an area behind GMT, your Date object might point to the 23rd of September, instead of the 24th.

If you want to create a date that is in local time with a date string, you need to include the time, e.g. new Date(2022-09-24T00:00:00).

Creating a Date object using a date string can be quite confusing, so it's best to use multiple, comma-separated parameters instead.

A safe approach is to pass the year, month (January = 0, February = 1, etc), day, hour, minutes and seconds values as comma-separated parameters to the constructor.

If you don't have values for the time, you can just pass the year, month (zero-based) and day of the month as parameters when creating the Date object.

In the example, we had a date and time string, formatted as YYYY-MM-DD hh:mm:ss, but this could be any other format.

The first thing we did was split the date and time string on the space, so we can get the date and time components as separate strings.

We then had to split the date string on each hyphen to get the value for the month, day and year. Note that your separator might be different, e.g. a forward slash, but the approach is the same.

We also split the time string on each colon and assigned the hours, minutes and seconds to variables.

Notice that we subtracted 1 from the month when passing it to the Date() constructor.

This is because, the Date constructor expects a zero-based value, where January = 0, February = 1, March = 2, etc.

We passed all of the parameters to the Date() constructor to create a Date object and got the correct value from the getDate() method.

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