TypeScript Functional Decorators w/ usecases

class Human {    stamina: number;    constructor(stamina: number) {        this.stamina = stamina;    }    run(requiredStamina: number): number {        return (this.stamina -= requiredStamina);    }    rest(addedStamina: number): number {        return (this.stamina += addedStamina);    }}const human = new Human(10);console.log(`Stamina before run: ` + human.stamina);human.run(1);console.log(`Stamina after run: ` + human.stamina);console.log(`Stamina before rest: ` + human.stamina);human.rest(12);console.log(`Stamina after rest: ` + human.stamina);console.log(`Stamina before run: ` + human.stamina);human.run(20);console.log(`Stamina after run: ` + human.stamina);// Stamina before run: 10// Stamina after run: 9// Stamina before rest: 9// Stamina after rest: 21// Stamina before run: 21// Stamina after run: 1

class Human {    stamina: number;    constructor(stamina: number) {        this.stamina = stamina;    }    @log    run(requiredStamina: number): number {        return (this.stamina -= requiredStamina);    }    @log    rest(addedStamina: number): number {        return (this.stamina += addedStamina);    }}function log(    target: Object,    propertyKey: string,    descriptor: TypedPropertyDescriptor<any>) {    const originalMethod = descriptor.value; // save a reference to the original method    // NOTE: Do not use arrow syntax here. Use a function expression in    // order to use the correct value of `this` in this method (see notes below)    descriptor.value = function (...args: any[]) {        // pre        console.log(`Stamina before ${propertyKey}: ` + args);        // run and store result        const result = originalMethod.apply(this, args);        // post        console.log(`Stamina after ${propertyKey}: ` + result);        // return the result of the original method (or modify it before returning)        return result;    };    return descriptor;}const human = new Human(10);human.run(1);human.rest(12);human.run(20);// Stamina before run: 1// Stamina after run: 9// Stamina before rest: 12// Stamina after rest: 21// Stamina before run: 20// Stamina after run: 1