jQuery, as well as other libraries.
jscript/jscript_xxxxxxx.* files are common places to check for direct references to old libraries. You will also want to check the
includes/templates/YOURTEMPLATE/jscript folder to see if there are old versions stored there.
A very easy way to test whether your libraries are current is to use Google Lighthouse utility. In Google Chrome, right click and select “Inspect.”
Then in the dialog that comes up, on the right side, click “Lighthouse.”
Click the Generate Report button, and look under “Best Practices.” The second error message in this screenshot indicates some libraries need updating.