Replaced fetch by promisified xmlhttprequest (#61)

src/checkInternetAccess.js

@@ -1,21 +1,20 @@
 /* @flow */
+import makeHttpRequest from './makeHttpRequest';
 
 export default function checkInternetAccess(
   timeout: number = 3000,
-  address: string = 'https://google.com',
+  url: string = 'https://google.com',
 ): Promise<boolean> {
   return new Promise((resolve: (value: boolean) => void) => {
-    const tm = setTimeout(() => {
-      resolve(false);
-    }, timeout);
-
-    fetch(address, { method: 'HEAD' })
+    makeHttpRequest({
+      method: 'HEAD',
+      url,
+      timeout,
+    })
       .then(() => {
-        clearTimeout(tm);
         resolve(true);
       })
       .catch(() => {
-        clearTimeout(tm);
         resolve(false);
       });
   });

src/makeHttpRequest.js

@@ -0,0 +1,76 @@
+/* @flow */
+
+type Options = {
+  method?: string,
+  url: string,
+  params?:
+    | string
+    | {
+        [name: string]: string,
+      },
+  headers?: Object,
+  timeout?: number,
+};
+
+/**
+ * Utility that promisifies XMLHttpRequest in order to have a nice API that supports cancellation.
+ * @param method
+ * @param url
+ * @param params -> This is the body payload for POST requests
+ * @param headers
+ * @param timeout -> Timeout for rejecting the promise and aborting the API request
+ * @returns {Promise}
+ */
+export default function makeHttpRequest(
+  { method = 'get', url, params, headers, timeout = 10000 }: Options = {},
+) {
+  return new Promise((resolve: any, reject: any) => {
+    const xhr = new XMLHttpRequest();
+
+    const tOut = setTimeout(() => {
+      xhr.abort();
+      reject('timeout');
+    }, timeout);
+
+    xhr.open(method, url);
+    xhr.onload = function onLoad() {
+      if (this.status >= 200 && this.status < 300) {
+        clearTimeout(tOut);
+        resolve(xhr.response);
+      } else {
+        clearTimeout(tOut);
+        reject({
+          status: this.status,
+          statusText: xhr.statusText,
+        });
+      }
+    };
+    xhr.onerror = function onError() {
+      clearTimeout(tOut);
+      reject({
+        status: this.status,
+        statusText: xhr.statusText,
+      });
+    };
+    if (headers) {
+      Object.keys(headers).forEach((key: string) => {
+        xhr.setRequestHeader(key, headers[key]);
+      });
+    }
+    let requestParams = params;
+    // We'll need to stringify if we've been given an object
+    // If we have a string, this is skipped.
+    if (requestParams && typeof requestParams === 'object') {
+      requestParams = Object.keys(requestParams)
+        .map(
+          (key: string) =>
+            `${encodeURIComponent(key)}=${encodeURIComponent(
+              // $FlowFixMe
+              requestParams[key],
+            )}`,
+        )
+        .join('&');
+    }
+    xhr.send(params);
+  });
+}