https://developer.mozilla.org/en-US/docs/Web/API/NetworkInformation

NetworkInformation.downlink Read only

Returns the effective bandwidth estimate in megabits per second, rounded to the nearest multiple of 25 kilobits per seconds.

NetworkInformation.downlinkMax Read only

Returns the maximum downlink speed, in megabits per second (Mbps), for the underlying connection technology.

NetworkInformation.effectiveType Read only

Returns the effective type of the connection meaning one of 'slow-2g', '2g', '3g', or '4g'. This value is determined using a combination of recently observed round-trip time and downlink values.

NetworkInformation.rtt Read only

Returns the estimated effective round-trip time of the current connection, rounded to the nearest multiple of 25 milliseconds.

NetworkInformation.saveData Read only

Returns true if the user has set a reduced data usage option on the user agent.

NetworkInformation.type Read only

Returns the type of connection a device is using to communicate with the network. It will be one of the following values:

bluetooth
cellular
ethernet
none
wifi
wimax
other
unknown