Moving default adapter to global defaults

lib/core/dispatchRequest.js

@@ -2,10 +2,10 @@
 
 var utils = require('./../utils');
 var transformData = require('./transformData');
+var defaults = require('../defaults');
 
 /**
- * Dispatch a request to the server using whichever adapter
- * is supported by the current environment.
+ * Dispatch a request to the server using the configured adapter.
  *
  * @param {object} config The config that is to be used for the request
  * @returns {Promise} The Promise to be fulfilled
@@ -35,41 +35,27 @@ module.exports = function dispatchRequest(config) {
     }
   );
 
-  var adapter;
+  var adapter = config.adapter || defaults.adapter;
 
-  if (typeof config.adapter === 'function') {
-    // For custom adapter support
-    adapter = config.adapter;
-  } else if (typeof XMLHttpRequest !== 'undefined') {
-    // For browsers use XHR adapter
-    adapter = require('../adapters/xhr');
-  } else if (typeof process !== 'undefined') {
-    // For node use HTTP adapter
-    adapter = require('../adapters/http');
-  }
+  return adapter(config).then(function onAdapterResolution(response) {
+    // Transform response data
+    response.data = transformData(
+      response.data,
+      response.headers,
+      config.transformResponse
+    );
 
-  return Promise.resolve(config)
-    // Wrap synchronous adapter errors and pass configuration
-    .then(adapter)
-    .then(function onFulfilled(response) {
-      // Transform response data
-      response.data = transformData(
-        response.data,
-        response.headers,
+    return response;
+  }, function onAdapterRejection(error) {
+    // Transform response data
+    if (error && error.response) {
+      error.response.data = transformData(
+        error.response.data,
+        error.response.headers,
         config.transformResponse
       );
+    }
 
-      return response;
-    }, function onRejected(error) {
-      // Transform response data
-      if (error && error.response) {
-        error.response.data = transformData(
-          error.response.data,
-          error.response.headers,
-          config.transformResponse
-        );
-      }
-
-      return Promise.reject(error);
-    });
+    return Promise.reject(error);
+  });
 };

lib/defaults.js

@@ -14,7 +14,21 @@ function setContentTypeIfUnset(headers, value) {
   }
 }
 
+function getDefaultAdapter() {
+  var adapter;
+  if (typeof XMLHttpRequest !== 'undefined') {
+    // For browsers use XHR adapter
+    adapter = require('./adapters/xhr');
+  } else if (typeof process !== 'undefined') {
+    // For node use HTTP adapter
+    adapter = require('./adapters/http');
+  }
+  return adapter;
+}
+
 module.exports = {
+  adapter: getDefaultAdapter(),
+
   transformRequest: [function transformRequest(data, headers) {
     normalizeHeaderName(headers, 'Content-Type');
     if (utils.isFormData(data) ||