MutationObserver strategy fails when script included in <head> #34

edsrzf · 2020-06-22T01:52:38Z

The MutationObserver strategy fails when the script defining elements is included inside the <head> tag, without using defer or async on the script tag. The error is:

Uncaught TypeError: Failed to execute 'observe' on 'MutationObserver': parameter 1 is not of type 'Node'.

The site of the error is here:

remount/src/strategies/mutation_observer.js

Lines 76 to 79 in 8bd440e

 observer.observe(document.body, { 

 childList: true, 

 subtree: true 

 })

The cause is that, inside <head> where the script is being evaluated, document.body does not yet exist.

Here is a repl.it link demonstrating the issue: https://repl.it/@EvanShaw2/Remount-MutationObserver-strategy-issue (This code forces all browsers to use the MutationObserver strategy, even if they support custom elements.)

It would be possible to get around this by calling Remount.define inside a jQuery $().ready event handler or equivalent native JS, which would ensure that document.body exists.

It would be nice if this limitation were documented. Even better if it were handled by remount itself.

The text was updated successfully, but these errors were encountered:

rstacruz · 2022-04-09T14:35:46Z

Interesting - maybe it can also observe document.body || document.documentElement instead 🤔

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MutationObserver strategy fails when script included in <head> #34

MutationObserver strategy fails when script included in <head> #34

edsrzf commented Jun 22, 2020

rstacruz commented Apr 9, 2022 •

edited

MutationObserver strategy fails when script included in <head> #34

MutationObserver strategy fails when script included in <head> #34

Comments

edsrzf commented Jun 22, 2020

rstacruz commented Apr 9, 2022 • edited

rstacruz commented Apr 9, 2022 •

edited