bradtraversy · July 29, 2025 23:59 · Aug 18, 2021 · Aug 17, 2021
diff --git a/typescript-crash.ts b/typescript-crash.ts
@@ -10,7 +10,7 @@ let arr: any[] = [1, true, 'Hello']
 // Tuple
 let person: [number, string, boolean] = [1, 'Brad', true]
 // Tuple Array
-let employee: [number, string][]
+let employees: [number, string][]
 
 employee = [
   [1, 'Brad'],
@@ -126,4 +126,4 @@ function getArray<T>(items: T[]): T[] {
 let numArray = getArray<number>([1, 2, 3, 4])
 let strArray = getArray<string>(['brad', 'John', 'Jill'])
 
-strArray.push(1)
+strArray.push(1) // Throws error
diff --git a/typescript-crash.ts b/typescript-crash.ts
@@ -0,0 +1,129 @@
+// Basic Types
+let id: number = 5
+let company: string = 'Traversy Media'
+let isPublished: boolean = true
+let x: any = 'Hello'
+
+let ids: number[] = [1, 2, 3, 4, 5]
+let arr: any[] = [1, true, 'Hello']
+
+// Tuple
+let person: [number, string, boolean] = [1, 'Brad', true]
+// Tuple Array
+let employee: [number, string][]
+
+employee = [
+  [1, 'Brad'],
+  [2, 'John'],
+  [3, 'Jill'],
+]
+
+// Union
+let pid: string | number
+pid = '22'
+
+// Enum
+enum Direction1 {
+  Up = 1,
+  Down,
+  Left,
+  Right,
+}
+
+enum Direction2 {
+  Up = 'Up',
+  Down = 'Down',
+  Left = 'Left',
+  Right = 'Right',
+}
+
+// Objects
+type User = {
+  id: number
+  name: string
+}
+
+const user: User = {
+  id: 1,
+  name: 'John',
+}
+
+// Type Assertion
+let cid: any = 1
+// let customerId = <number>cid
+let customerId = cid as number
+
+// Functions
+function addNum(x: number, y: number): number {
+  return x + y
+}
+
+// Void
+function log(message: string | number): void {
+  console.log(message)
+}
+
+// Interfaces
+interface UserInterface {
+  readonly id: number
+  name: string
+  age?: number
+}
+
+const user1: UserInterface = {
+  id: 1,
+  name: 'John',
+}
+
+interface MathFunc {
+  (x: number, y: number): number
+}
+
+const add: MathFunc = (x: number, y: number): number => x + y
+const sub: MathFunc = (x: number, y: number): number => x - y
+
+interface PersonInterface {
+  id: number
+  name: string
+  register(): string
+}
+
+// Classes
+class Person implements PersonInterface {
+  id: number
+  name: string
+
+  constructor(id: number, name: string) {
+    this.id = id
+    this.name = name
+  }
+
+  register() {
+    return `${this.name} is now registered`
+  }
+}
+
+const brad = new Person(1, 'Brad Traversy')
+const mike = new Person(2, 'Mike Jordan')
+
+// Subclasses
+class Employee extends Person {
+  position: string
+
+  constructor(id: number, name: string, position: string) {
+    super(id, name)
+    this.position = position
+  }
+}
+
+const emp = new Employee(3, 'Shawn', 'Developer')
+
+// Generics
+function getArray<T>(items: T[]): T[] {
+  return new Array().concat(items)
+}
+
+let numArray = getArray<number>([1, 2, 3, 4])
+let strArray = getArray<string>(['brad', 'John', 'Jill'])
+
+strArray.push(1)