TypeScript class decorator that modifies object instance

Question

I\'m making a plugin for Aurelia and need a class decorator that

1. adds attributes to the new object instance, and
2. calls an external function with the new

Answer 1

Here's a working version:

function addAndCall(target: any) {
    var original = target;

    function construct(constructor, args) {
        var c: any = function () {
            this.newAttribute = "object instance value";
            ExternalModule.externalFunction(this);
            return constructor.apply(this, args);;
        }

        c.prototype = constructor.prototype;
        return new c();
    }

    var f: any = function (...args) {
        return construct(original, args);
    }

    f.prototype = original.prototype;
    return f;
}

(code in playground)