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.

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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

# Constant

Version 2.7 brings the possibility of accessing a property using a constant and symbol. This is a minor improvement because, before 2.7, it was possible to access (read and write) a constant or symbol, but not to define a field in an interface or type.


const Foo = "Foo"; // Constant value
const Bar = "Bar"; // Constant value
const Zaz = "Zaz"; // Constant value

const objectWithConstantProperties = { [Foo]: 100, [Bar]: "hello", [Zaz]: () => {} };

let a12: number = objectWithConstantProperties[Foo];
let b2334: string = objectWithConstantProperties[Bar];

console.log(a12);
console.log(b2334);

The example defined three constants on lines **1, 2, and 3**. On **line 5**, the constants are used in the identifier part (between the square brackets) to assign values. On **lines 7-8**, the constant is reused for accessing the values.

The idea behind using a constant is to avoid miswriting a string.

In this lesson, we will study how to use keys with constants and symbols.


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

Keys with Constants and Symbols

Constant