How is a “detection tool” such Dell SupportAssist able to detect if it is installed on a system through the web browser?

When I access a site such as in order to locate drivers for my device, some sites, such as Dell, provide “smart” support that detect your system, check certain parameters, and then return the matching drivers based, most likely, on the service tag retrieved.

I understand in order to work it needs the matching executable to run; however, the web site itself appears to be able to “detect” whether or not the tool (in this case, Dell SupportAssist) is installed. If a browser doesn’t have access to the file system, how is this accomplished? I assume it is some sort of plug-in for the browser that grants the browser extended access to the system?

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