javascript - How to recognize the function is the class constructor and how to call it as a function? -

i'm little bit confused class feature in es2016, though assumed syntax sugar creating classes, in comparison function , prototype, behaviour in cases different, in particular - classes can't called same functions , seems, there no way find out if function class constructor or simple function, without using tostring , /^class/ regexp.

assume example:

class foo {     constructor () {         this.name = 'foo';     } } function bar () {     this.name = 'bar'; }  function dosmth (anyarg) {     if (typeof anyarg === 'function') {         var obj = { someprop: 'qux' };         anyarg.call(obj);         return obj;     }     // ... }   dosmth(bar); dosmth(foo); // class constructor foo cannot invoked without 'new' 

is typeof 'function', can't call function! nice.

and here 2 questions:

1. is there way can call foo constructor function same bar overriden this context?
2. is there way can detect anyarg constructor of class, sothat can handle differently in dosmth function. without tostring , regexp (as performance penalty huge in case). use reflect.construct initialize new instance, , object.assign extend obj variable values instance.

thank you, alex

no both questions.

here's how angular 1.x detects classes:

function isclass(func) {   // ie 9-11 not support classes , ie9 leaks code below.   if (msie <= 11 || typeof func !== 'function') {     return false;   }   var result = func.$$ngisclass;   if (!isboolean(result)) {     // support: edge 12-13     // see: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/6156135/     result = func.$$ngisclass = /^(?:class\b|constructor\()/.test(stringifyfn(func));   }   return result; } 

unfortunately, it's best possible solution. , doesn't work in firefox @ that.