Can't define custom element in IE11 - "custom element constructors must be functions" error

[webcomponents]

Can't define custom element in IE11 - "custom element constructors must be functions" error

[bicknellr]

IE11 doesn't have support for Reflect; are you doing some type of transpilation step? Any other info?

[snuggs]

@lexigren #ping

[SerkanSipahi]

@lexigren This error appears in custom-elements v0, too, when you try to extend "HTMLElement" thats constructor is not a function. This is not a custom-elements problem, its an IE, Safari respectively a engine/vendor problem.

You can resolve it by mapping the constructor to a function!

if (typeof HTMLElement === 'object'){
     let _Element = function(){};
     _Element.prototype = HTMLElement.prototype;
     HTMLElement = _Element;
}