chore: more notes on typescript typing course

Author: okeeffed

public/content/.obsidian/core-plugins.json

@@ -13,6 +13,5 @@
   "markdown-importer",
   "outline",
   "word-count",
-  "open-with-default-app",
   "file-recovery"
-]
+]

public/content/.obsidian/workspace

@@ -9,7 +9,7 @@
         "state": {
           "type": "markdown",
           "state": {
-            "file": "javascript/testing-javascript/6-Testing-React-Components-With-Jest-And-React-Testing-Library.md",
+            "file": "typescript/Noted-To-Merge.md",
             "mode": "source",
             "source": false
           }
@@ -69,7 +69,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "javascript/testing-javascript/6-Testing-React-Components-With-Jest-And-React-Testing-Library.md",
+                "file": "typescript/Noted-To-Merge.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -86,7 +86,7 @@
             "state": {
               "type": "outgoing-link",
               "state": {
-                "file": "javascript/testing-javascript/6-Testing-React-Components-With-Jest-And-React-Testing-Library.md",
+                "file": "typescript/Noted-To-Merge.md",
                 "linksCollapsed": false,
                 "unlinkedCollapsed": true
               }
@@ -109,7 +109,7 @@
             "state": {
               "type": "outline",
               "state": {
-                "file": "javascript/testing-javascript/6-Testing-React-Components-With-Jest-And-React-Testing-Library.md"
+                "file": "typescript/Noted-To-Merge.md"
               }
             }
           }
@@ -122,6 +122,13 @@
   },
   "active": "81afcea829cb47b4",
   "lastOpenFiles": [
+    "typescript/ts-fundamentals-v2.md",
+    "typescript/production-typescript-course.md",
+    "typescript/getting-started.md",
+    "typescript/enforcing-prop-names.md",
+    "typescript/developers-guide.md",
+    "typescript/duck-typing.md",
+    "typescript/Typescript.md",
     "javascript/testing-javascript/6-Testing-React-Components-With-Jest-And-React-Testing-Library.md",
     "javascript/testing-javascript/5-Configure-Jest-For-Testing-JS-Apps.md"
   ]

public/content/typescript/Noted-To-Merge.md

@@ -0,0 +1,156 @@
+# Making TypeScript Stick
+
+## Compiling TypeScript
+
+### Will it compile?
+
+```ts
+// YES
+let age = 38
+
+age = Number.NaN
+
+// YES - Unfortunately, because tuples are a specialized flavor of arrays (and at runtime, they actually are just regular arrays) they expose the entire array API. Look at the type signature of `.push()`
+const vector3: [number, number, number] = [3, 4, 5]
+
+vector3.push(6)
+
+// NO - Duplicate identifier
+type Color = {
+  red: number
+  green: number
+  blue: number
+}
+
+interface Color {
+  alpha: number
+}
+
+// NO - no initializer and is not definitely assigned in constructor
+class Person {
+  name: string
+  friends: Person[]
+
+  constructor(name: string) {
+    this.name = name
+  }
+}
+
+// NO - Property 'name' in type 'Student' is not assignable to the same property in base type 'Person'.
+abstract class Person {
+  public abstract name: string
+}
+
+class Student extends Person {
+  public name: string | string[] = ['Mike North']
+}
+
+// NO - not assignable to type Color
+interface Color {
+  red: number
+  green: number
+  blue: number
+}
+
+function printColor(color: Color) {
+  // ... //
+}
+
+printColor({
+  red: 255,
+  green: 0,
+  blue: 0,
+  alpha: 0.4,
+})
+```
+
+## Challenges
+
+### Typerdy
+
+This section was a typing challenge.
+
+## Type Challenges
+
+This is a [repo](https://github.com/type-challenges/type-challenges) to practice your typing.
+
+The difficulty is subjective, so don't get too frustrated if some of the medium come off as difficult.
+
+Challenge 1:
+
+```ts
+// @errors: 2344
+
+type Expect<T extends true> = T
+
+type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y
+  ? 1
+  : 2
+  ? true
+  : false
+
+type NotEqual<X, Y> = true extends Equal<X, Y> ? false : true
+
+// ---cut---
+
+// Implement this type
+
+type If<C, T, F> = never
+
+// Tests
+
+type cases = [
+  Expect<Equal<If<true, 'apple', 'pear'>, 'apple'>>,
+
+  Expect<Equal<If<false, 'orange', 42>, 42>>
+]
+```
+
+The answer:
+
+```ts
+// Implement this type
+
+type If<C, T, F> = C extends true ? T : F
+```
+
+Challenge 2:
+
+```ts
+// @errors: 2344
+
+type Expect<T extends true> = T
+
+type Equal<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y
+  ? 1
+  : 2
+  ? true
+  : false
+
+type NotEqual<X, Y> = true extends Equal<X, Y> ? false : true
+
+// ---cut---
+
+// Implement this type
+
+type LengthOfTuple<T> = never
+
+// Tests
+
+const Fruits = ['cherry', 'banana'] as const
+
+type cases = [
+  Expect<Equal<LengthOfTuple<[1, 2, 3]>, 3>>,
+  Expect<NotEqual<LengthOfTuple<[1, 2, 3]>, 2>>,
+  Expect<Equal<LengthOfTuple<typeof Fruits>, 2>>,
+  Expect<Equal<LengthOfTuple<[]>, 0>>
+]
+```
+
+The answer:
+
+```ts
+// Implement this type
+
+type LengthOfTuple<T> = T extends readonly any[] ? T['length'] : never
+```