fix: don't treat non-function on* props on custom elements as event handlers#5170
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JoviDeCroock wants to merge 1 commit into
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fix: don't treat non-function on* props on custom elements as event handlers#5170JoviDeCroock wants to merge 1 commit into
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…andlers Custom elements may expose non-event attributes starting with "on" (e.g. only-when-overflow). Only take the event-listener path when the new or old value is a function, or the element is not a custom element (no dash in its tag name). The typeof check short-circuits first, so regular event handlers pay no extra cost. Fixes #4085
JoviDeCroock
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Jul 18, 2026
| else if ( | ||
| name[0] == 'o' && | ||
| name[1] == 'n' && | ||
| (typeof value == 'function' || |
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short-circuit so there shouldn't be an extra cost for normal execution)
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coverage: 98.541%. remained the same — JoviDeCroock/issue-4085 into main |
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IMO, we shouldn't support this.
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I mean, onlyOverflow for instance is a valid name for a prop and it runs into this issue. I think it's a non obvious footgun. I guess it has propagated in the ecosystem so we can live with it, tried to see if we had some easy fixes |
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Custom elements may expose non-event attributes starting with "on" (e.g. only-when-overflow). Only take the event-listener path when the new or old value is a function, or the element is not a custom element (no dash in its tag name).
Fixes #4085
Co-Authored with GPT5.6-sol for tests