TypeScript 4.0
Class Property Inference from Constructors
TypeScript 4.0 can now use control flow analysis to determine the types of properties in JavaScript Class Notation 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;
}
}