Update date.js

[lucasrla]

@ganevru, I am experiencing the same described here: #25

This tiny PR isn't the most elegant one, but it does prevent the issue from happening. (Since this is my first PR here, I decided to go as simple as possible.)

A solution to consider in the future (depending on your plans) is to add a timeZone option in siteMetadata (gatsby-config.js) and then parse it appropriately inside date.js.

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The root cause of the issue is that in our frontmatters (as per the starters examples) we input dates in the following format:

date: 2020-08-13

When you insert that string into the Date constructor, Date objects are (implicitly) created with 00:00:00 time and UTC as their time zone:

// https://github.com/Chronoblog/gatsby-theme-chronoblog/blob/master/packages/gatsby-theme-chronoblog/src/components/date.js#L14
const newDate = new Date(date);

Then, when you convert the newDate using toLocaleString(language, options) to our local time zones, things can get weird.

Because @reallymello (Florida) and I live in time zones that are UTC-3 (or more) we noticed the issue. All our posts/notes/links are showed in the feed with the frontmatter day minus 1.

I assume you haven't noticed anything on your side because it seems you live in Moscow (which is UTC+3, give or take). Your days are never shifted!

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Well, that's a very long explanation for such a tiny PR. 😅

In any case, thanks again for creating this great theme!

[ganevdev]

Thanks for the detailed explanation, this is a good practice even for small code changes.