Alternative to decorate function in TypeScript

Question

Since TypeScript allows decorate only class, method, property or setter/getter because of hoisting, is there any way to decorate a raw function? Or maybe something similar to decoration mechanism or even write own custom mechanism to avoid TypeScript rules.

Answer 1

Technically this is not one of the "TypeScript rules" but a problem with JavaScript. It is yet not syntactically possible to use @decorator for functions, but in its essence, a function decorator is just a higher-order function that wraps around the decorated function.

The closest thing that you can do is defining a function wrapper

function foo() {
    return "asd";
}

const wrap = (func: () => void) => {
    const wrapped = () => {
         console.log("wrapped");
         return func();
    }
    return wrapped;
}

console.log(wrap(foo)());