Gain insights into TypeScript's core concepts, from basics to advanced type checking and iterators. Learn about static typing and JS library support through practical, hands-on experience.

TypeScriptBasic.tar.gz

TypeScript Latest and Strict

check ts version

TypeScript-assert

TypeScript-assert-copy

If you’re looking to move beyond vanilla JavaScript and take your skills to the next level, then you’ve come to the right place. TypeScript is an in-demand language that sits on top of JavaScript. This means you can do everything you can in JavaScript with TypeScript, but also enjoy countless other perks including support for JS libraries, NPM, static typing, and much more.

In this course, you’ll start from the beginning and work your way up to more advanced concepts like type checking, iterators, and manipulating objects and arrays. You'll get a chance to get your hands dirty with plenty of real practice along the way.

For JavaScript developers, TypeScript is a must-know language, not only for today but also for years to come. Don't miss out.

Learn TypeScript: The Complete Course for Beginners

You can use `extends` to extend a generic type to another type if you want the generic type to be a subset of the other type. 

In the following code, we see that **line 13** expects that the generic `K` extends `T`, which means that the second parameter needs to extend the former.

interface TypeA {
  prop1: string;
  prop2: number;
}
interface TypeB {
  prop1: string;
  prop3: boolean;
}
interface TypeC extends TypeA {
  prop4: number;
}

function printProps<T, K extends T>(p1: T, p2: K): void { // K must have all field from T at minimum
  console.log(p1);
  console.log(p2);
}

let a: TypeA = { prop1: "p1", prop2: 2 };
let b: TypeB = { prop1: "p1", prop3: true };
let c: TypeC = { prop1: "p1", prop2: 2, prop4: 4 };


// printProps(a, b); // Does not transpile because B does not extends A
printProps(a, c);

The commented code on **line 23** does not transpile because `TypeB` is not extending `TypeA`. However, **line 24** is successful because `TypeC` extends `TypeA` on **line 9** which means that `TypeC` has all its properties merged with `TypeA` properties.


This lesson explains how to combine keyof with generic.

Introduction

The Basics of Variables

Comment

Enum

Generic Type

Functions

Mapped Type

Objects

Index Signature

Variables Advanced

Exception

Alias

Type Checking

Iterators

Manipulating Objects and Array

Sharing Code

Conclusion

Generic and keyof