[ReactNative] NetworkInformation.reachability API w/ example

Libraries/Network/NetInfo.js

@@ -0,0 +1,143 @@
+/**
+ * Copyright 2004-present Facebook. All Rights Reserved.
+ *
+ * @providesModule NetInfo
+ * @flow
+ */
+'use strict';
+
+var NativeModules = require('NativeModules');
+var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
+var RKReachability = NativeModules.RKReachability;
+
+var DEVICE_REACHABILITY_EVENT = 'reachabilityDidChange';
+
+type ChangeEventName = $Enum<{
+  change: string;
+}>;
+
+
+/**
+ * NetInfo exposes info about online/offline status
+ *
+ * == iOS Reachability
+ *
+ * Asyncronously determine if the device is online and on a cellular network.
+ *
+ * - "none" - device is offline
+ * - "wifi" - device is online and connected via wifi, or is the iOS simulator
+ * - "cell" - device is connected via Edge, 3G, WiMax, or LTE
+ * - "unknown" - error case and the network status is unknown
+ *
+ * ```
+ * NetInfo.reachabilityIOS.fetch().done((reach) => {
+ *   console.log('Initial: ' + reach);
+ * });
+ * function handleFirstReachabilityChange(reach) {
+ *   console.log('First change: ' + reach);
+ *   NetInfo.reachabilityIOS.removeEventListener(
+ *     'change',
+ *     handleFirstReachabilityChange
+ *   );
+ * }
+ * NetInfo.reachabilityIOS.addEventListener(
+ *   'change',
+ *   handleFirstReachabilityChange
+ * );
+ * ```
+ */
+
+var NetInfo = {};
+
+if (RKReachability) {
+  var _reachabilitySubscriptions = {};
+
+  NetInfo.reachabilityIOS = {
+    addEventListener: function (
+      eventName: ChangeEventName,
+      handler: Function
+    ): void {
+      _reachabilitySubscriptions[handler] = RCTDeviceEventEmitter.addListener(
+        DEVICE_REACHABILITY_EVENT,
+        (appStateData) => {
+          handler(appStateData.network_reachability);
+        }
+      );
+    },
+
+    removeEventListener: function(
+      eventName: ChangeEventName,
+      handler: Function
+    ): void {
+      if (!_reachabilitySubscriptions[handler]) {
+        return;
+      }
+      _reachabilitySubscriptions[handler].remove();
+      _reachabilitySubscriptions[handler] = null;
+    },
+
+    fetch: function(): Promise {
+      return new Promise((resolve, reject) => {
+        RKReachability.getCurrentReachability(
+          (resp) => {
+            resolve(resp.network_reachability);
+          },
+          reject
+        );
+      });
+    },
+  };
+
+  /**
+   *
+   * == NetInfo.isConnected
+   *
+   * Available on all platforms. Asyncronously fetch a boolean to determine
+   * internet connectivity.
+   *
+   * ```
+   * NetInfo.isConnected.fetch().done((isConnected) => {
+   *   console.log('First, is ' + (isConnected ? 'online' : 'offline'));
+   * });
+   * function handleFirstConnectivityChange(isConnected) {
+   *   console.log('Then, is ' + (isConnected ? 'online' : 'offline'));
+   *   NetInfo.isConnected.removeEventListener(
+   *     'change',
+   *     handleFirstConnectivityChange
+   *   );
+   * }
+   * NetInfo.isConnected.addEventListener(
+   *   'change',
+   *   handleFirstConnectivityChange
+   * );
+   * ```
+   *
+   */
+  var _isConnectedSubscriptions = {};
+  NetInfo.isConnected = {
+    addEventListener: function (
+      eventName: ChangeEventName,
+      handler: Function
+    ): void {
+      _isConnectedSubscriptions[handler] = (reachability) => {
+        handler(reachability !== 'none');
+      };
+      NetInfo.reachabilityIOS.addEventListener(eventName, _isConnectedSubscriptions[handler]);
+    },
+
+    removeEventListener: function(
+      eventName: ChangeEventName,
+      handler: Function
+    ): void {
+      NetInfo.reachabilityIOS.removeEventListener(eventName, _isConnectedSubscriptions[handler]);
+    },
+
+    fetch: function(): Promise {
+      return NetInfo.reachabilityIOS.fetch().then(
+        (reachability) => reachability !== 'none'
+      );
+    },
+  };
+}
+
+module.exports = NetInfo;