Object.setPrototypeOf() is a performance killer

[jlgrall]

core/src/registerRoot.js

Lines 28 to 29 in 12250ef

	Object.setPrototypeOf(proto, parentProto)
	Object.setPrototypeOf(RootElement, parentConstructor)

Hi, I read the article Writing a JavaScript Framework - The Benefits of Custom Elements. And I have been thinking about the use of Object.setPrototypeOf() which is a performance killer.

Why could you not use Object.create() ? What would be missing if you used Object.create()?

[jlgrall]

Maybe with something like this you could get rid of the Object.setPrototypeOf() and still have the right constructor be executed on instanciations:

var parent = HTMLElement;
var RootElement = function() {
    console.log("Executing RootElement ctor.");
    return Reflect.construct(HTMLElement.constructor, [], RootElement);
};

// Used to make the new class extends its parent:
var protoChainingProxy = function() { }; // This function can actually be reused or cached, it doesn't have to be re-created each time.
// Prepare prototype chaining to the parent:
protoChainingProxy.prototype = parent.prototype;
// Make the prototype's chain from RootElement to it's parent:
var proto = RootElement.prototype = new protoChainingProxy;
proto.constructor = RootElement;	// This is not required, but is good conduct and might be expected from other libs

console.log(RootElement);
console.log(new RootElement());
console.log(new RootElement() instanceof HTMLElement); // true

Copy-paste in your js console to test it.