fix(synthetic-shadow): conservatively disable focus navigation routine upon focus #2077
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⚠ Performance RegressionBest has detected that there is a Please click here to see more details. Click to view significantly changed benchmarks@lwc/engine-dom
@lwc/engine-server
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jodarove
reviewed
Nov 9, 2020
| .shadowRoot.querySelector('integration-child') | ||
| .shadowRoot.querySelector('button'); | ||
| }); | ||
| button.click(); // click into input |
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clicks the input or the button?
jodarove
reviewed
Nov 9, 2020
| static delegatesFocus = true; | ||
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| handleFocus(event) { | ||
| event.target.focus(); |
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does the button (event.target) already have the focus before calling .focus()?
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what confuses me is that the button will get the focus even if we don't execute this line. but i also guess that executing this line without the fix, will make the test fail.
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Yeah, it doesn’t make sense but we should be able to handle that!
🥳 Performance ImprovementBest has detected that there is a Please click here to see more details. Click to view significantly changed benchmarks@lwc/engine-dom
@lwc/engine-server
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jodarove
approved these changes
Nov 9, 2020
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Details
In a nutshell, this is how we disable keyboard focus navigation when the user clicks on an element:
mousedown:letBrowserHandleFocusis set totruefocusin: short circuit the keyboard focus navigation routine ifletBrowserHandleFocusis set totruemouseup:letBrowserHandleFocusis set tofalseThe problem here is that, during a
click, allfocusevents are processed beforefocusinevents, so if there is a focus handler that runs between themousedownandfocusinevents above, and it invokes thefocus()method on an element (which is a very strange behavior), theletBrowserHandleFocusflag is incorrectly set tofalsebefore ourfocusinhandler runs, causing the "next" element to be incorrectly focused.Does this PR introduce breaking changes?
No, it does not introduce breaking changes.GUS work item
N/A yet