Firefox: disable the leave page dialog box
Many malware websites continually throw the dialog box: Are you sure you want to leave this webpage? They do this to prevent you from closing the window. This article explains how to turn off the dialog box in Firefox.
To turn off the Firefox dialog box for leaving a webpage:

enter about:config into the firefox address bar (confirm the info message in case it shows up)

search for the preference named dom.disable_beforeunload. double-click it

change its value to true.

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