Add Extract Object Type Values Into A Union Type as a TypeScript TIL

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).
 
-_1211 TILs and counting..._
+_1213 TILs and counting..._
 
 ---
 
@@ -1028,6 +1028,7 @@ _1211 TILs and counting..._
 - [Silence The Output Of A Ruby Statement In Pry](ruby/silence-the-output-of-a-ruby-statement-in-pry.md)
 - [Single And Double Quoted String Notation](ruby/single-and-double-quoted-string-notation.md)
 - [Skip Specific CVEs When Auditing Your Bundle](ruby/skip-specific-cves-when-auditing-your-bundle.md)
+- [Specify Dependencies For A Rake Task](ruby/specify-dependencies-for-a-rake-task.md)
 - [Squeeze Out The Extra Space](ruby/squeeze-out-the-extra-space.md)
 - [String Interpolation With Instance Variables](ruby/string-interpolation-with-instance-variables.md)
 - [Summing Collections](ruby/summing-collections.md)
@@ -1117,6 +1118,7 @@ _1211 TILs and counting..._
 - [Add Types To An Object Destructuring](typescript/add-types-to-an-object-destructuring.md)
 - [Compiler Checks For Unused Params And Variables](typescript/compiler-checks-for-unused-params-and-variables.md)
 - [Extract Object Type Keys Into A Union Type](typescript/extract-object-type-keys-into-a-union-type.md)
+- [Extract Object Type Values Into A Union Type](typescript/extract-object-type-values-into-a-union-type.md)
 - [Interfaces With The Same Name Are Merged](typescript/interfaces-with-the-same-name-are-merged.md)
 - [Re-Export An Imported Type](typescript/re-export-an-imported-type.md)
 - [Type Narrowing With Similarly Shaped Objects](typescript/type-narrowing-with-similarly-shaped-objects.md)

ruby/specify-dependencies-for-a-rake-task.md

@@ -0,0 +1,37 @@
+# Specify Dependencies For A Rake Task
+
+Let's say you have rake task that performs some important business task. For
+instance, a book seller might want a task that can tell them the top selling
+books from a CSV report.
+
+```ruby
+task :top_selling_books do
+  # read in CSV and process for top selling books
+end
+```
+
+This works great if the CSV file already exists on the machine from which this
+task is run. What if it isn't tho?
+
+The CSV is a prerequesite for this task. We explicitly define it as a
+prerequisite using the task dependency syntax.
+
+```ruby
+task :download_latest_book_sales_csv do
+  # saves a CSV of book sales
+end
+
+task top_selling_books: :download_latest_book_sales_csv do
+  # read in CSV and process for top selling books
+end
+```
+
+We can even define multiple task dependencies with an array.
+
+```ruby
+task top_selling_books: [:download_latest_book_sales_csv, :clean_csv] do
+  # read in CSV and process for top selling books
+end
+```
+
+[source](https://subscription.packtpub.com/book/hardware_and_creative/9781783280773/1/ch01lvl1sec13/task-dependencies-prerequisites)

typescript/extract-object-type-values-into-a-union-type.md

@@ -0,0 +1,54 @@
+# Extract Object Type Values Into A Union Type
+
+Let's say we have an object type like the following:
+
+```typescript
+type GlobalReducerEvent = {
+    ADD_TODO: {
+        text: string
+    }
+    LOG_IN: {
+        email: string
+    }
+    DELETE_TODO: {
+        todo_id: number
+    }
+}
+```
+
+We can use the [indexed access
+type](https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html)
+to access the value indexed at one the type keys. This works a lot like
+JavaScript's object access.
+
+```typescript
+type AddTodoType = GlobalReducerEvent['ADD_TODO'];
+/*
+type AddTodoType = {
+  text: string
+}
+*/
+```
+
+Where it gets more interesting and differs from JavaScript's object access is
+when we do an indexed access of a union type.
+
+```typescript
+type TypesForEvents = GlobalReducerEvent[keyof GlobalReducerEvent];
+/*
+type TypesForEvents = {
+  text: string
+} | {
+  email: string
+} | {
+  todo_id: number
+}
+*/
+```
+
+The result is a union of each of the values whose keys had matches in the
+union.
+
+Where this gets more interesting and useful is when we use it as part of a
+mapped type like I explore in [Breaking Down a Complex Mapped
+Type](https://dev.to/jbranchaud/breaking-down-a-complex-mapped-type-in5).