Originally posted by@koto in#4409 (comment)

I noticed one violation still injQuery.attr, where the value of the attributeis stringified before callingsetAttribute:

const policy = trustedTypes.createPolicy('a', {createScriptURL: s=>s})jQuery(aScript, policy.createScriptURL('foo'));Uncaught TypeError: Failed to execute 'setAttribute' on 'Element': This document requires 'TrustedScriptURL' assignment.    at attr (jquery.js:6997)    at access (jquery.js:3467)    at jQuery.fn.init.attr (jquery.js:6955)    at <anonymous>:1:6

There is a workaround via.attr hooks, but it might be worth addressing nonetheless.

It seems like this was introduced inff75767, I suspect to workaround anIE <= 9 bug, which incorrectly stringified objects passed tosetAttribute.

I'm not sure what the most elegant solution would be here, I guess it depends on whether jQuery 4 aims to support IE9. If not, it's safe not to stringify values (browser API would). If yes, then there's only a less-than-ideal option of testing for the bug? IIRC this would be a good test:

with (document.createElement('div')) {  setAttribute('title', {toString:()=>''});   getAttribute('title') === ''}