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total-typescript · Aug 16, 2023 · 65e21f8 · 65e21f8
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diff --git a/...ing/037-introduction-to-unions.problem.ts → ...ing/037-introduction-to-unions.problem.ts b/...ing/037-introduction-to-unions.problem.ts → ...ing/037-introduction-to-unions.problem.ts
diff --git a/...ng/037-introduction-to-unions.solution.ts → ...ng/037-introduction-to-unions.solution.ts b/...ng/037-introduction-to-unions.solution.ts → ...ng/037-introduction-to-unions.solution.ts
diff --git a/...nd-narrowing/038-literal-types.problem.ts → ...nd-narrowing/038-literal-types.problem.ts b/...nd-narrowing/038-literal-types.problem.ts → ...nd-narrowing/038-literal-types.problem.ts
diff --git a/...narrowing/038-literal-types.solution.1.ts → ...narrowing/038-literal-types.solution.1.ts b/...narrowing/038-literal-types.solution.1.ts → ...narrowing/038-literal-types.solution.1.ts
diff --git a/...narrowing/038-literal-types.solution.2.ts → ...narrowing/038-literal-types.solution.2.ts b/...narrowing/038-literal-types.solution.2.ts → ...narrowing/038-literal-types.solution.2.ts
diff --git a/...narrowing/039-combining-unions.problem.ts → ...narrowing/039-combining-unions.problem.ts b/...narrowing/039-combining-unions.problem.ts → ...narrowing/039-combining-unions.problem.ts
diff --git a/...arrowing/039-combining-unions.solution.ts → ...arrowing/039-combining-unions.solution.ts b/...arrowing/039-combining-unions.solution.ts → ...arrowing/039-combining-unions.solution.ts
diff --git a/...g/040-how-big-can-a-union-be.explainer.ts → ...g/040-how-big-can-a-union-be.explainer.ts b/...g/040-how-big-can-a-union-be.explainer.ts → ...g/040-how-big-can-a-union-be.explainer.ts
diff --git a/.../041-literals-vs-wider-types.explainer.ts → .../041-literals-vs-wider-types.explainer.ts b/.../041-literals-vs-wider-types.explainer.ts → .../041-literals-vs-wider-types.explainer.ts
diff --git a/...narrowing-unions-with-typeof.explainer.ts → ...narrowing-unions-with-typeof.explainer.ts b/...narrowing-unions-with-typeof.explainer.ts → ...narrowing-unions-with-typeof.explainer.ts
diff --git a/...3-narrowing-with-if-statements.problem.ts → ...3-narrowing-with-if-statements.problem.ts b/...3-narrowing-with-if-statements.problem.ts → ...3-narrowing-with-if-statements.problem.ts
diff --git a/...arrowing-with-if-statements.solution.1.ts → ...arrowing-with-if-statements.solution.1.ts b/...arrowing-with-if-statements.solution.1.ts → ...arrowing-with-if-statements.solution.1.ts
diff --git a/...arrowing-with-if-statements.solution.2.ts → ...arrowing-with-if-statements.solution.2.ts b/...arrowing-with-if-statements.solution.2.ts → ...arrowing-with-if-statements.solution.2.ts
diff --git a/...arrowing-with-if-statements.solution.3.ts → ...arrowing-with-if-statements.solution.3.ts b/...arrowing-with-if-statements.solution.3.ts → ...arrowing-with-if-statements.solution.3.ts
diff --git a/...arrowing-with-if-statements.solution.4.ts → ...arrowing-with-if-statements.solution.4.ts b/...arrowing-with-if-statements.solution.4.ts → ...arrowing-with-if-statements.solution.4.ts
diff --git a/...arrowing-with-if-statements.solution.5.ts → ...arrowing-with-if-statements.solution.5.ts b/...arrowing-with-if-statements.solution.5.ts → ...arrowing-with-if-statements.solution.5.ts
diff --git a/...owing-with-boolean-wont-work.explainer.ts → ...owing-with-boolean-wont-work.explainer.ts b/...owing-with-boolean-wont-work.explainer.ts → ...owing-with-boolean-wont-work.explainer.ts
diff --git a/.../045-throwing-errors-to-narrow.problem.ts → .../045-throwing-errors-to-narrow.problem.ts b/.../045-throwing-errors-to-narrow.problem.ts → .../045-throwing-errors-to-narrow.problem.ts
diff --git a/...045-throwing-errors-to-narrow.solution.ts → ...045-throwing-errors-to-narrow.solution.ts b/...045-throwing-errors-to-narrow.solution.ts → ...045-throwing-errors-to-narrow.solution.ts
diff --git a/...ing-with-instanceof-statements.problem.ts → ...ing-with-instanceof-statements.problem.ts b/...ing-with-instanceof-statements.problem.ts → ...ing-with-instanceof-statements.problem.ts
diff --git a/...ng-with-instanceof-statements.solution.ts → ...ng-with-instanceof-statements.solution.ts b/...ng-with-instanceof-statements.solution.ts → ...ng-with-instanceof-statements.solution.ts
diff --git a/...7-narrowing-with-in-statements.problem.ts → ...7-narrowing-with-in-statements.problem.ts b/...7-narrowing-with-in-statements.problem.ts → ...7-narrowing-with-in-statements.problem.ts
diff --git a/...-narrowing-with-in-statements.solution.ts → ...-narrowing-with-in-statements.solution.ts b/...-narrowing-with-in-statements.solution.ts → ...-narrowing-with-in-statements.solution.ts
diff --git a/...8-narrowing-unknown-to-a-value.problem.ts → ...8-narrowing-unknown-to-a-value.problem.ts b/...8-narrowing-unknown-to-a-value.problem.ts → ...8-narrowing-unknown-to-a-value.problem.ts
diff --git a/...-narrowing-unknown-to-a-value.solution.ts → ...-narrowing-unknown-to-a-value.solution.ts b/...-narrowing-unknown-to-a-value.solution.ts → ...-narrowing-unknown-to-a-value.solution.ts
diff --git a/...g/049-narrowing-with-ternaries.problem.ts → ...g/049-narrowing-with-ternaries.problem.ts b/...g/049-narrowing-with-ternaries.problem.ts → ...g/049-narrowing-with-ternaries.problem.ts
diff --git a/.../049-narrowing-with-ternaries.solution.ts → .../049-narrowing-with-ternaries.solution.ts b/.../049-narrowing-with-ternaries.solution.ts → .../049-narrowing-with-ternaries.solution.ts
diff --git a/...rowing-with-nullish-coalescing.problem.ts → ...rowing-with-nullish-coalescing.problem.ts b/...rowing-with-nullish-coalescing.problem.ts → ...rowing-with-nullish-coalescing.problem.ts
diff --git a/...owing-with-nullish-coalescing.solution.ts → ...owing-with-nullish-coalescing.solution.ts b/...owing-with-nullish-coalescing.solution.ts → ...owing-with-nullish-coalescing.solution.ts
diff --git a/...-intro-to-discriminated-unions.problem.ts → ...-intro-to-discriminated-unions.problem.ts b/...-intro-to-discriminated-unions.problem.ts → ...-intro-to-discriminated-unions.problem.ts
diff --git a/...intro-to-discriminated-unions.solution.ts → ...intro-to-discriminated-unions.solution.ts b/...intro-to-discriminated-unions.solution.ts → ...intro-to-discriminated-unions.solution.ts
diff --git a/...ucturing-a-discriminated-union.problem.ts → ...ucturing-a-discriminated-union.problem.ts b/...ucturing-a-discriminated-union.problem.ts → ...ucturing-a-discriminated-union.problem.ts
diff --git a/...cturing-a-discriminated-union.solution.ts → ...cturing-a-discriminated-union.solution.ts b/...cturing-a-discriminated-union.solution.ts → ...cturing-a-discriminated-union.solution.ts
diff --git a/...-union-with-a-switch-statement.problem.ts → ...-union-with-a-switch-statement.problem.ts b/...-union-with-a-switch-statement.problem.ts → ...-union-with-a-switch-statement.problem.ts
diff --git a/...union-with-a-switch-statement.solution.ts → ...union-with-a-switch-statement.solution.ts b/...union-with-a-switch-statement.solution.ts → ...union-with-a-switch-statement.solution.ts
diff --git a/...4-narrowing-with-switch-true.explainer.ts → ...4-narrowing-with-switch-true.explainer.ts b/...4-narrowing-with-switch-true.explainer.ts → ...4-narrowing-with-switch-true.explainer.ts
diff --git a/...ucturing-a-discriminated-tuple.problem.ts → ...ucturing-a-discriminated-tuple.problem.ts b/...ucturing-a-discriminated-tuple.problem.ts → ...ucturing-a-discriminated-tuple.problem.ts
diff --git a/...cturing-a-discriminated-tuple.solution.ts → ...cturing-a-discriminated-tuple.solution.ts b/...cturing-a-discriminated-tuple.solution.ts → ...cturing-a-discriminated-tuple.solution.ts
diff --git a/...ing/056-discriminated-booleans.problem.ts → ...ing/056-discriminated-booleans.problem.ts b/...ing/056-discriminated-booleans.problem.ts → ...ing/056-discriminated-booleans.problem.ts
diff --git a/...ng/056-discriminated-booleans.solution.ts → ...ng/056-discriminated-booleans.solution.ts b/...ng/056-discriminated-booleans.solution.ts → ...ng/056-discriminated-booleans.solution.ts
diff --git a/src/020-sets-of-types/057-extend-object-using-intersections.problem.ts b/src/020-sets-of-types/057-extend-object-using-intersections.problem.ts
@@ -0,0 +1,38 @@
+type User = {
+  id: string;
+  createdAt: Date;
+  name: string;
+  email: string;
+};
+
+type Product = {
+  id: string;
+  createdAt: Date;
+  name: string;
+  price: number;
+};
+
+type tests = [
+  Expect<
+    Extends<
+      User,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        email: string;
+      }
+    >
+  >,
+  Expect<
+    Extends<
+      Product,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        price: number;
+      }
+    >
+  >,
+];
diff --git a/src/020-sets-of-types/057-extend-object-using-intersections.solution.ts b/src/020-sets-of-types/057-extend-object-using-intersections.solution.ts
@@ -0,0 +1,39 @@
+type BaseEntity = {
+  id: string;
+  createdAt: Date;
+};
+
+type User = {
+  name: string;
+  email: string;
+} & BaseEntity;
+
+type Product = {
+  name: string;
+  price: number;
+} & BaseEntity;
+
+type tests = [
+  Expect<
+    Extends<
+      User,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        email: string;
+      }
+    >
+  >,
+  Expect<
+    Extends<
+      Product,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        price: number;
+      }
+    >
+  >,
+];
diff --git a/src/020-sets-of-types/058-extend-object-using-interfaces.problem.ts b/src/020-sets-of-types/058-extend-object-using-interfaces.problem.ts
@@ -0,0 +1,39 @@
+type BaseEntity = {
+  id: string;
+  createdAt: Date;
+};
+
+type User = {
+  name: string;
+  email: string;
+} & BaseEntity;
+
+type Product = {
+  name: string;
+  price: number;
+} & BaseEntity;
+
+type tests = [
+  Expect<
+    Extends<
+      User,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        email: string;
+      }
+    >
+  >,
+  Expect<
+    Extends<
+      Product,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        price: number;
+      }
+    >
+  >,
+];
diff --git a/src/020-sets-of-types/058-extend-object-using-interfaces.solution.1.ts b/src/020-sets-of-types/058-extend-object-using-interfaces.solution.1.ts
@@ -0,0 +1,39 @@
+interface BaseEntity {
+  id: string;
+  createdAt: Date;
+}
+
+interface User extends BaseEntity {
+  name: string;
+  email: string;
+}
+
+interface Product extends BaseEntity {
+  name: string;
+  price: number;
+}
+
+type tests = [
+  Expect<
+    Extends<
+      User,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        email: string;
+      }
+    >
+  >,
+  Expect<
+    Extends<
+      Product,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        price: number;
+      }
+    >
+  >,
+];
diff --git a/src/020-sets-of-types/058-extend-object-using-interfaces.solution.2.ts b/src/020-sets-of-types/058-extend-object-using-interfaces.solution.2.ts
@@ -0,0 +1,42 @@
+interface WithId {
+  id: string;
+}
+
+interface WithCreatedAt {
+  createdAt: Date;
+}
+
+interface User extends WithId, WithCreatedAt {
+  name: string;
+  email: string;
+}
+
+interface Product extends WithId, WithCreatedAt {
+  name: string;
+  price: number;
+}
+
+type tests = [
+  Expect<
+    Extends<
+      User,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        email: string;
+      }
+    >
+  >,
+  Expect<
+    Extends<
+      Product,
+      {
+        id: string;
+        createdAt: Date;
+        name: string;
+        price: number;
+      }
+    >
+  >,
+];
diff --git a/src/020-sets-of-types/059-compare-between-intersections-and-interfaces.explainer.ts b/src/020-sets-of-types/059-compare-between-intersections-and-interfaces.explainer.ts
@@ -0,0 +1 @@
+// https://github.com/microsoft/TypeScript/wiki/Performance#preferring-interfaces-over-intersections
diff --git a/src/020-sets-of-types/060-index-signatures.problem.ts b/src/020-sets-of-types/060-index-signatures.problem.ts
@@ -0,0 +1,5 @@
+const scores = {};
+
+scores.math = 95;
+scores.english = 90;
+scores.science = 85;
diff --git a/src/020-sets-of-types/060-index-signatures.solution.1.ts b/src/020-sets-of-types/060-index-signatures.solution.1.ts
@@ -0,0 +1,9 @@
+type Scores = {
+  [key: string]: number;
+};
+
+const scores: Scores = {};
+
+scores.math = 95;
+scores.english = 90;
+scores.science = 85;
diff --git a/src/020-sets-of-types/060-index-signatures.solution.2.ts b/src/020-sets-of-types/060-index-signatures.solution.2.ts
@@ -0,0 +1,9 @@
+interface Scores {
+  [key: string]: number;
+}
+
+const scores: Scores = {};
+
+scores.math = 95;
+scores.english = 90;
+scores.science = 85;
diff --git a/src/020-sets-of-types/060-index-signatures.solution.3.ts b/src/020-sets-of-types/060-index-signatures.solution.3.ts
@@ -0,0 +1,7 @@
+const scores: {
+  [key: string]: number;
+} = {};
+
+scores.math = 95;
+scores.english = 90;
+scores.science = 85;
diff --git a/src/020-sets-of-types/060-index-signatures.solution.4.ts b/src/020-sets-of-types/060-index-signatures.solution.4.ts
@@ -0,0 +1,5 @@
+const scores: Record<string, number> = {};
+
+scores.math = 95;
+scores.english = 90;
+scores.science = 85;
diff --git a/src/020-sets-of-types/061-index-signatures-with-defined-keys.problem.ts b/src/020-sets-of-types/061-index-signatures-with-defined-keys.problem.ts
@@ -0,0 +1,16 @@
+interface Scores {
+  [key: string]: number;
+  math: number;
+  english: number;
+  science: number;
+}
+
+// @ts-expect-error science is missing!
+const scores: Scores = {
+  math: 95,
+  english: 90,
+};
+
+scores.athletics = 100;
+scores.french = 75;
+scores.spanish = 70;
diff --git a/src/020-sets-of-types/061-index-signatures-with-defined-keys.solution.1.ts b/src/020-sets-of-types/061-index-signatures-with-defined-keys.solution.1.ts
@@ -0,0 +1,16 @@
+interface Scores {
+  [key: string]: number;
+  math: number;
+  english: number;
+  science: number;
+}
+
+// @ts-expect-error science is missing!
+const scores: Scores = {
+  math: 95,
+  english: 90,
+};
+
+scores.athletics = 100;
+scores.french = 75;
+scores.spanish = 70;
diff --git a/src/020-sets-of-types/061-index-signatures-with-defined-keys.solution.2.ts b/src/020-sets-of-types/061-index-signatures-with-defined-keys.solution.2.ts
@@ -0,0 +1,19 @@
+interface RequiredScores {
+  math: number;
+  english: number;
+  science: number;
+}
+
+interface Scores extends RequiredScores {
+  [key: string]: number;
+}
+
+// @ts-expect-error science is missing!
+const scores: Scores = {
+  math: 95,
+  english: 90,
+};
+
+scores.athletics = 100;
+scores.french = 75;
+scores.spanish = 70;
diff --git a/src/020-sets-of-types/062-record-type-with-union-as-keys.problem.ts b/src/020-sets-of-types/062-record-type-with-union-as-keys.problem.ts
diff --git a/src/020-sets-of-types/062-record-type-with-union-as-keys.solution.ts b/src/020-sets-of-types/062-record-type-with-union-as-keys.solution.ts
diff --git a/src/020-sets-of-types/063-declaration-merging-of-interfaces.problem.ts b/src/020-sets-of-types/063-declaration-merging-of-interfaces.problem.ts
@@ -0,0 +1,19 @@
+interface Logger {
+  log(message: string, level: number): void;
+}
+
+interface Logger {
+  log(message: string): void;
+}
+
+const myLogger: Logger = {
+  log: (message: string) => {
+    console.log(message);
+  },
+};
+
+myLogger.log(
+  "My message",
+  // @ts-expect-error Level is NOT needed
+  123,
+);
diff --git a/src/020-sets-of-types/063-declaration-merging-of-interfaces.solution.ts b/src/020-sets-of-types/063-declaration-merging-of-interfaces.solution.ts
@@ -0,0 +1,15 @@
+type Logger = {
+  log(message: string): void;
+};
+
+const myLogger: Logger = {
+  log: (message: string) => {
+    console.log(message);
+  },
+};
+
+myLogger.log(
+  "My message",
+  // @ts-expect-error Level is NOT needed
+  123,
+);
diff --git a/src/020-sets-of-types/064-pick-type-helper.problem.ts b/src/020-sets-of-types/064-pick-type-helper.problem.ts
@@ -0,0 +1,18 @@
+interface User {
+  id: string;
+  name: string;
+  email: string;
+  role: string;
+}
+
+const fetchUser = async () => {
+  const response = await fetch("/api/user");
+  const user = await response.json();
+  return user;
+};
+
+const example = async () => {
+  const user = await fetchUser();
+
+  type test = Expect<Equal<typeof user, { name: string; email: string }>>;
+};
diff --git a/src/020-sets-of-types/064-pick-type-helper.solution.1.ts b/src/020-sets-of-types/064-pick-type-helper.solution.1.ts
@@ -0,0 +1,21 @@
+interface NameAndEmail {
+  name: string;
+  email: string;
+}
+
+interface User extends NameAndEmail {
+  id: string;
+  role: string;
+}
+
+const fetchUser = async (): Promise<NameAndEmail> => {
+  const response = await fetch("/api/user");
+  const user = await response.json();
+  return user;
+};
+
+const example = async () => {
+  const user = await fetchUser();
+
+  type test = Expect<Equal<typeof user, { name: string; email: string }>>;
+};
diff --git a/src/020-sets-of-types/064-pick-type-helper.solution.2.ts b/src/020-sets-of-types/064-pick-type-helper.solution.2.ts
@@ -0,0 +1,20 @@
+interface User {
+  id: string;
+  name: string;
+  email: string;
+  role: string;
+}
+
+type OnlyNameAndEmail = Pick<User, "name" | "email">;
+
+const fetchUser = async (): Promise<OnlyNameAndEmail> => {
+  const response = await fetch("/api/user");
+  const user = await response.json();
+  return user;
+};
+
+const example = async () => {
+  const user = await fetchUser();
+
+  type test = Expect<Equal<typeof user, { name: string; email: string }>>;
+};