Merge 15337dfd71 into 51880975d4

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1423 TILs and counting..._
+_1429 TILs and counting..._
 
 ---
 
@@ -261,6 +261,7 @@ _1423 TILs and counting..._
 
 - [Accessing a Lost Commit](git/accessing-a-lost-commit.md)
 - [Add A Range Of Filename To gitignore](git/add-a-range-of-filenames-to-gitignore.md)
+- [Add Only Tracked Files From A Directory](git/add-only-tracked-files-from-a-directory.md)
 - [Amend Author Of Previous Commit](git/amend-author-of-previous-commit.md)
 - [Auto-Squash Those Fixup Commits](git/auto-squash-those-fixup-commits.md)
 - [Caching Credentials](git/caching-credentials.md)
@@ -320,6 +321,7 @@ _1423 TILs and counting..._
 - [Quicker Commit Fixes With The Fixup Flag](git/quicker-commit-fixes-with-the-fixup-flag.md)
 - [Rebase Commits With An Arbitrary Command](git/rebase-commits-with-an-arbitrary-command.md)
 - [Reference A Commit Via Commit Message Pattern Matching](git/reference-a-commit-via-commit-message-pattern-matching.md)
+- [Remove Untracked Files From A Directory](git/remove-untracked-files-from-a-directory.md)
 - [Rename A Remote](git/rename-a-remote.md)
 - [Renaming A Branch](git/renaming-a-branch.md)
 - [Resetting A Reset](git/resetting-a-reset.md)
@@ -460,6 +462,7 @@ _1423 TILs and counting..._
 - [Find Where Yarn Is Installing Binaries](javascript/find-where-yarn-is-installing-binaries.md)
 - [for...in Iterates Over Object Properties](javascript/for-in-iterates-over-object-properties.md)
 - [Format A Decimal To A Fixed Number Of Digits](javascript/format-a-decimal-to-a-fixed-number-of-digits.md)
+- [Format Time Zone Identifier](javascript/format-time-zone-identifier.md)
 - [Formatting Values With Units For Display](javascript/formatting-values-with-units-for-display.md)
 - [Freeze An Object, Sorta](javascript/freeze-an-object-sorta.md)
 - [Generate A V4 UUID In The Browser](javascript/generate-a-v4-uuid-in-the-browser.md)
@@ -608,6 +611,7 @@ _1423 TILs and counting..._
 - [List Databases And Tables](mysql/list-databases-and-tables.md)
 - [Run Statements In A Transaction](mysql/run-statements-in-a-transaction.md)
 - [Select Rows After An Offset](mysql/select-rows-after-an-offset.md)
+- [Set Value On Null JSON Column](mysql/set-value-on-null-json-column.md)
 - [Show Create Statement For A Table](mysql/show-create-statement-for-a-table.md)
 - [Show Tables That Match A Pattern](mysql/show-tables-that-match-a-pattern.md)
 - [Show Indexes For A Table](mysql/show-indexes-for-a-table.md)
@@ -1374,7 +1378,9 @@ _1423 TILs and counting..._
 - [Fix Unlinked Node Binaries With asdf](unix/fix-unlinked-node-binaries-with-asdf.md)
 - [Forward Multiple Ports Over SSH](unix/forward-multiple-ports-over-ssh.md)
 - [Generate A SAML Key And Certificate Pair](unix/generate-a-saml-key-and-certificate-pair.md)
+- [Generate Base64 Encoding Without Newlines](unix/generate-base64-encoding-without-newlines.md)
 - [Generate Random 20-Character Hex String](unix/generate-random-20-character-hex-string.md)
+- [Get A List Of Locales On Your System](unix/get-a-list-of-locales-on-your-system.md)
 - [Get Matching Filenames As Output From Grep](unix/get-matching-filenames-as-output-from-grep.md)
 - [Get The Unix Timestamp](unix/get-the-unix-timestamp.md)
 - [Global Substitution On The Previous Command](unix/global-substitution-on-the-previous-command.md)

git/add-only-tracked-files-from-a-directory.md

@@ -0,0 +1,26 @@
+# Add Only Tracked Files From A Directory
+
+The two extremes of staging files in a git repo are to either selectively pick
+each individual chunk of changes with `git add --patch` (my preference!) or to
+run `git add -A` to add everything.
+
+Now let's say I have large directory full of files that get generated during
+test runs. Most of these files are tracked (already checked in to the
+repository). There are also many new files generated as part of the most recent
+test run.
+
+I want to staging the changes to files that are already tracked, but hold off
+on doing anything with the new files.
+
+Running `git add spec/cassettes` won't do the track because that will pull in
+everything. Running `git add --patch spec/cassettes` will take long and be
+tedious. Instead what I want is the `-u` flag. It's short for _update_ which
+means it will only stage already tracked files.
+
+```bash
+$ git add -u spec/cassettes
+```
+
+That will stage every change to any already known files in `spec/cassettes`.
+
+See `man git-add` for more details.

git/remove-untracked-files-from-a-directory.md

@@ -0,0 +1,26 @@
+# Remove Untracked Files From A Directory
+
+Let's say I have a directory (`spec/cassettes`) full of a ton of generated YAML
+files. Most of these files are tracked by git. However, I just generated a
+bunch of new ones that are untracked. For whatever reason, I don't want these
+files. I need to delete them.
+
+Running `rm` on each of them is going to be too tedious. And it is tricky to
+target them for a bulk delete since there are a ton of other files in that
+directory that I want to keep.
+
+One way to approach this is have `git ls-files` help out with listing all files in the
+directory that are untracked. The `--others` flag filters to untracked files.
+
+```bash
+git ls-files --others --exclude-standard spec/cassettes
+```
+
+From there, I can pipe it to `rm` (with `xargs` collapsing all the files into a
+single line):
+
+```bash
+git ls-files --others --exclude-standard spec/cassettes | xargs rm
+```
+
+See `man git-ls-files` for more details.

javascript/format-time-zone-identifier.md

@@ -0,0 +1,34 @@
+# Format Time Zone Identifier
+
+Though there are surely libraries that can help with this task, we now have
+full support in the [`Intl.DateTimeFormat`
+API](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat)
+for formatting a date's time zone identifier in various ways.
+
+To do this, we have to create a formatter specifying the locale, the `timeZone`
+option, and any formatting options. For the formatting, I'll try the
+`timeZoneName` with both `short` and `longGeneric`.
+
+Then we `formatToParts` on any date object and extract the `timeZoneName`
+value:
+
+```javascript
+const options = { timeZone: 'America/Chicago', timeZoneName: "short" }
+const formatter = new Intl.DateTimeFormat("en-US", options)
+
+formatter.formatToParts(new Date()).find((part) => part.type === "timeZoneName").value
+//=> 'CDT'
+```
+
+Now, let's try this for `longGeneric`:
+
+```javascript
+const options = { timeZone: 'America/Chicago', timeZoneName: "longGeneric" }
+const formatter = new Intl.DateTimeFormat("en-US", options)
+
+formatter.formatToParts(new Date()).find((part) => part.type === "timeZoneName").value
+//=> 'Central Time'
+```
+
+There are several more options for the `timeZoneName` as well as a bunch more
+you can do with the `Intl.DateTimeFormat` API.

mysql/set-value-on-null-json-column.md

@@ -0,0 +1,44 @@
+# Set Value On Null JSON Column
+
+To set a key-value pair on a JSON field, you can reach for
+[MySQL's `json_set`](https://dev.mysql.com/doc/refman/8.0/en/json-modification-functions.html#function_json-set)
+or one of [the other JSON setter
+functions](https://dev.mysql.com/doc/refman/8.0/en/json-modification-functions.html).
+
+However, if the JSON field you are updating is `null`, you might get an
+unexpected result.
+
+```sql
+> update User
+    set metadata = json_set(metadata, '$.discord_id', 'discord_123')
+    where id = 123;
+
+Query OK, 0 rows affected (0.00 sec)
+Rows matched: 1  Changed: 0  Warnings: 0
+```
+
+We can see that the `where` clause matched on a single row as expected, but
+right above that it says _0 rows affected_.
+
+What happened?
+
+The `json_set` function is not able to set a key-value pair on `null`. It needs
+a JSON object to work on.
+
+There are a number of ways to get around this. I find that
+[`coalesce`](https://dev.mysql.com/doc/refman/8.0/en/comparison-operators.html#function_coalesce)
+is a natural way to handle this. If `metadata` happens to be `null`, then we
+_coalesce_ it to `'{}'` (an empty object).
+
+```sql
+> update User
+    set metadata = json_set(coalesce(metadata, '{}'), '$.discord_id', 'discord_123')
+    where id = 123;
+
+Query OK, 1 row affected (0.02 sec)
+Rows matched: 1  Changed: 1  Warnings: 0
+```
+
+It updates as expected. That same statement will work on a row where `metadata`
+already contains a JSON object since the `coalesce` will resolve to that
+instead of the empty object.

unix/generate-base64-encoding-without-newlines.md

@@ -0,0 +1,25 @@
+# Generate Base64 Encoding Without Newlines
+
+There are a variety of tools that can generate a Base64 encoding of given text.
+Most of them that I've encountered have a number of characters at which they
+introduce a newline character. Here is `openssl` as an example:
+
+```bash
+❯ echo "here is a long bit of text to base64 encode with openssl" | openssl base64
+aGVyZSBpcyBhIGxvbmcgYml0IG9mIHRleHQgdG8gYmFzZTY0IGVuY29kZSB3aXRo
+IG9wZW5zc2wK
+```
+
+[The theory I've seen](https://superuser.com/a/1225139) is that this is to
+accommodate 80-character terminal screens when chunks of encoding were included
+in emails.
+
+With the `openssl base64` command, there is not an option to exclude the
+newlines, but we can pipe it through `tr` to remove them.
+
+```bash
+❯ echo "here is a long bit of text to base64 encode with openssl" | \
+  openssl base64 | \
+  tr -d '\n'
+aGVyZSBpcyBhIGxvbmcgYml0IG9mIHRleHQgdG8gYmFzZTY0IGVuY29kZSB3aXRoIG9wZW5zc2wK
+```

unix/get-a-list-of-locales-on-your-system.md

@@ -0,0 +1,36 @@
+# Get A List Of Locales On Your System
+
+The `locale -a` command will list all the available locales on your system.
+
+You'll see a giant list that probably includes these and many more values.
+
+```bash
+$ locale -a
+
+en_NZ
+nl_NL.UTF-8
+pt_BR.UTF-8
+fr_CH.ISO8859-15
+eu_ES.ISO8859-15
+en_US.US-ASCII
+af_ZA
+bg_BG
+cs_CZ.UTF-8
+fi_FI
+zh_CN.UTF-8
+eu_ES
+sk_SK.ISO8859-2
+nl_BE
+fr_BE
+sk_SK
+en_US.UTF-8
+...
+```
+
+Each of these locales identifies itself by the language and the manner in which
+the language is used in a particular place. For example, `en_NZ` is _English as
+it is spoken in New Zealand_. `fr_BE` is _French as it is spoken in Belgium_.
+`en_US.UTF-8` is _English as it is spoken in the US, with a UTF-8 character set
+encoding_.
+
+[source](https://www.postgresql.org/docs/current/locale.html#LOCALE-OVERVIEW)