wrapConstructor.js

(function () {
    function wrapConstructor(OriginalClass, OnInitFunc) {
        const functionBody = `
            const WrappereClass = function () {
                OriginalClass.apply(this, arguments);
                if (OnInitFunc) OnInitFunc.call(this);
            };
            WrappereClass.prototype = Object.create(OriginalClass.prototype);
            WrappereClass.prototype.constructor = WrappereClass;
            return WrappereClass;
        `.replace(/WrappereClass/g, OriginalClass.name);
        return (new Function('OriginalClass', 'OnInitFunc', functionBody))(OriginalClass, OnInitFunc);
    }

    (function App() {
        function class1(a, b) {
            this.a = a;
            this.b = b;
        }

        let class2 = wrapConstructor(class1, function () {
            console.log('after creating: ', this);
        });
        let value1 = new class2('a', 'b');
        let value2 = new class2('c', 'd');
        console.log({
            value1: value1,
            value2: value2,
            instanceof_class1: value1 instanceof class1,
            instanceof_class2: value1 instanceof class2
        });
    })();
})();