Install TypeScript

npm install -g typescript

Compile TypeScript into JavaScript

tsc filename.ts

Examples

// JavaScript
const input1 = document.getElementById("num1")
const input2 = document.getElementById("num2")
// TypeScript
const input1 = document.getElementById("num1")! as HTNLInputElement
const input2 = document.getElementById("num2")! as HTNLInputElement

// JavaScript
function add(num1, num2){
    return num1 + num2
}
// TypeScript
function add(num1: number, num2: number){
    return num1 + num2
}

// JavaScript
button.addEventListener("click", function(){
    console.log( add(input1.value, input2.value))
})
// TypeScript : add + before string to become number
button.addEventListener("click", function(){
    console.log( add(+input1.value, +input2.value))
})

TypeScript adds : Types!, Next-gen JavaScript Features (compiled down for older browsers), Non-JavaScript Features like Interfaces or Generics, Meta-Programming Features like Decorators, Rich Configuration Options, Modern Tooling that helps even in non-TypeScript Projects

Timestamps

Getting Started (00:00)
What is TypeScript: (01:57)
Installing & Using TypeScript (06:31)
The Advantages of TypeScript (19:53)
Course Outline (22:59)
How to Get the Most out of This Course (27:16)
Setting Up our Development Environment (30:29)
The Course Project Setup (33:36)
Module Introduction (40:56)
Using Types (41:23)
TypeScript Types vs JavaScript Types (51:43)
Numbers, Strings and Booleans (56:37)
Type Assignment and Type Inference (01:02:20)
Object Types (01:07:59)
Array Types (01:15:31)
Tuples (01:21:01)
Enums (01:27:21)
The Any Type (01:34:26)
Union Types (01:36:30)
Literal Types (01:43:01)
Type Aliases (01:50:55)
Function Return Types and Void (01:53:55)
Function Types (02:01:21)
Function Types and Callbacks (02:06:55)
The Unknown Type (02:11:18)
The Never Type (02:15:02)
Wrap Up (02:19:12)
Module Introduction (02:21:04)
Watch Node (02:21:50)
Compiling the Entire Project (02:23:55)
Include and Exclude Files (02:27:42)
Setting a Compilation Target (02:33:55)
Understanding TypeScript Libs (02:37:59)
More Options (02:43:31)
Source Maps (02:45:12)
Rootdir and Outdir (02:47:12)
noemit on Error (02:52:43)
Strict Compilation Options (02:55:35)
Code Quality Options (03:06:39)
Debugging with Visual Studio Code (03:11:02)
Wrap Up (03:15:22)