Add Basic Date Formatting Without A Library as a javascript til

README.md

@@ -9,7 +9,7 @@ and pairing with smart people at Hashrocket.
 
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 ### JavaScript
 
 - [Accessing Arguments To A Function](javascript/accessing-arguments-to-a-function.md)
+- [Basic Date Formatting Without A Library](javascript/basic-date-formatting-without-a-library.md)
 - [Character Codes from Keyboard Listeners](javascript/character-codes-from-keyboard-listeners.md)
 - [Check If Something Is An Array](javascript/check-if-something-is-an-array.md)
 - [Check The Password Confirmation With Yup](javascript/check-the-password-confirmation-with-yup.md)

javascript/basic-date-formatting-without-a-library.md

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+# Basic Date Formatting Without A Library
+
+JavaScript, on modern browsers, has an Internationalization API that, among
+other things, provides some date formatting utilities. You can just start using
+it, no need to import some massive date formatting library.
+
+Here is a `Date` object:
+
+```javascript
+> const now = new Date();
+> now
+Tue Nov 19 2019 16:23:43 GMT-0600 (Central Standard Time)
+```
+
+The default formatting with this API is a good start:
+
+```javascript
+> Intl.DateTimeFormat('en-US').format(now)
+"11/19/2019"
+```
+
+There are also a number of options for more advanced formatting. Here is the
+`dateStyle` option with the four possible option values:
+
+```javascript
+> Intl.DateTimeFormat('en-US', { dateStyle: "full" }).format(now)
+"Tuesday, November 19, 2019"
+> Intl.DateTimeFormat('en-US', { dateStyle: "long" }).format(now)
+"November 19, 2019"
+> Intl.DateTimeFormat('en-US', { dateStyle: "medium" }).format(now)
+"Nov 19, 2019"
+> Intl.DateTimeFormat('en-US', { dateStyle: "short" }).format(now)
+"11/19/19"
+```
+
+There is a lot more to this API including localization and custom formatting.
+Check out the
+[docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat)
+for those details.