It should not be required that elements are JSON serializable

[Artur-]

When using the Shady DOM polyfill https://github.com/webcomponents/shadydom you will hit TypeError: cyclic object value when trying to return a list of elements from an execute script call (see webcomponents/shadydom#217).

It seems that webdrivers internally use JSON.stringify on the list of elements to return, which in turn runs JSON.stringify on the elements inside the list. While this works fine for the standard case, the Shady DOM polyfill adds a __shady property to the element and at least when the element contains children, the __shady property contains cycles and cannot thus be coverted to JSON. Now this implementation detail of __shady has seemingly absolutely nothing to do with returning an element from a webdriver but because of JSON.stringify, it won't work.

Returning a single element works fine as JSON.stringify does not seem to be used in that case.

[andreastt]

Did you run this against geckodriver?

[Artur-]

Example using FirefoxDriver + Selenium 3.9.1 in https://github.com/Artur-/selenium-shadydom

[whimboo]

Isn't there a way to just only care about the standard properties and attributes of DOM elements, and just ignore the custom ones? In case of Firefox it might work if we serialize the prototype of the expected DOM node(s).