The inspector shows the word "event" next to elements in the HTML Pane, that have event listeners bound to them:
Click the icon, then you'll see a popup listing all the event listeners bound to this element:
Each line contains:
- a right-pointing arrowhead; click to expand the row and show the listener function source code
- a curved arrow pointing to a stack; click it to show the code for the handler in the debugger
- the name of the event for which a handler was attached to this element
- the name and line number for the listener; you can also click here to expand the row and view the listener function source code
- a label indicating whether the event bubbles
- a label indicating the system that defines the event. Firefox can display:
- standard DOM events
- jQuery events
- React events