wiki/content/20201009104411-typescript_classes.md

id	title
b6fa7fa7-644f-42ab-bee6-71f4f58a60f2	TypeScript Classes

TypeScript 4.0

Class Property Inference from Constructors

TypeScript 4.0 can now use control flow analysis to determine the types of properties in classes when noImplicitAny is enabled.

class Square {
    // Previously: implicit any!
    // Now: inferred to `number`!
    area;
    sideLength;

    constructor(sideLength: number) {
        this.sideLength = sideLength;
        this.area = sideLength ** 2;
    }
}