It throw error if target element inside a iframe on Chrome

Describe the bug If we try observe an element inside iframe it will throw an error:

Failed to execute 'observe' on 'ResizeObserver': parameter 1 is not of type 'Element"

It because when you check target instanceof Element it return false. The reason are explained here: https://stackoverflow.com/questions/52222237/instanceof-fails-in-iframe

We can try other way to check target is an element like: https://stackoverflow.com/questions/384286/how-do-you-check-if-a-javascript-object-is-a-dom-object

Or use lodash.iselement: https://www.npmjs.com/package/lodash.iselement

To Reproduce Please try this demo on Chrome: https://codesandbox.io/s/pensive-cache-31co0

Expected behavior It work with element inside iframe.

Frameworks/Libraries used React

Desktop (please complete the following information):

• OS: Any
• Browser Chrome

[minhtranite]

Hi @JayaKrishnaNamburu your problem on the demo above easy to fix by use iframe document to create element instead of top windown document.

The demo for the fix: https://codesandbox.io/s/observer-330-forked-39xy9?file=/src/App.tsx

[TremayneChrist]

Great! I’m not sure if you’ve looked at the code yet but it’s probably best to just test if el instanceof Element first and return. If not, continue to try and find the document/window scope. This is the current issue for your use case, as the util cannot find out what the defaultView is.