// Get the connection type.
  var type = navigator.connection.type;

  // Get an upper bound on the downlink speed of the first network hop
  var max = navigator.connection.downlinkMax;

  function changeHandler(e) {
    // Handle change to connection here.
  }

  // Register for event changes.
  navigator.connection.onchange = changeHandler;

  // Alternatively.
  navigator.connection.addEventListener('change', changeHandler);
  

bluetooth

A Bluetooth connection.

cellular

A cellular connection (e.g., EDGE, HSPA, LTE, etc.).

ethernet

An Ethernet connection.

none

No network connection. The user agent will not contact the network when the user follows links or when a script requests a remote page (or knows that such an attempt would fail) - i.e., equivalent to navigator.onLine === false in HTML.

mixed

The user agent is using multiple connection types.

other

The connection type that is known, but not one of enumerated connection types.

unknown

The user agent has established a network connection, but is unable, or unwilling, to determine the underlying connection technology.

wifi

A Wi-Fi connection.

wimax

A WiMAX connection.

  enum ConnectionType {
    "bluetooth",
    "cellular",
    "ethernet",
    "mixed",
    "none",
    "other",
    "unknown",
    "wifi",
    "wimax"
  };

  enum EffectiveConnectionType {
    "2g",
    "3g",
    "4g",
    "slow-2g"
  };

  interface mixin NavigatorNetworkInformation {
    [SameObject] readonly attribute NetworkInformation connection;
  };

  Navigator includes NavigatorNetworkInformation;
  WorkerNavigator includes NavigatorNetworkInformation;

  [Exposed=(Window,Worker)]
  interface NetworkInformation : EventTarget {
    readonly attribute ConnectionType type;
    readonly attribute EffectiveConnectionType effectiveType;
    readonly attribute Megabit downlinkMax;
    readonly attribute Megabit downlink;
    readonly attribute Millisecond rtt;
    attribute EventHandler onchange;
  };

  typedef unrestricted double Megabit;
  typedef unsigned long long Millisecond;