Sometimes, you’ll notice that a background tab has an orange dot on it in Edge (or a blue dot in Chrome). If you click on the tab, the dot disappears.
Why?
The dot indicates that the tab wants “attention” — more specifically, that there’s a dialog in the tab asking for your attention. This might be a JavaScript alert() or confirm() dialog, or a prompt requesting permission to launch an Application Protocol:
Years ago, the dot also used to appear any time the title of a pinned tab changed (because pinned tabs don’t show their titles) but that code was removed in 2018.
Nowadays, web content cannot directly trigger the dot icon (short of showing an alert()) but some sites will draw their own indicator by updating their favicon using JavaScript:
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