add support for binary and serialized object-data responses (arraybuffer/json responseType)

Author: tchakabam

lib/index.js

@@ -1,5 +1,7 @@
 'use strict';
 
+/* global ArrayBuffer */
+
 /**
  * Node.js `XMLHttpRequest` implementation using `http.request()`.
  *
@@ -24,7 +26,11 @@ var supportedResponseTypes = Object.freeze({
   /** Text response (implicit) */
   '': true,
   /** Text response */
-  'text': true
+  'text': true,
+  /** Binary-data response */
+  'arraybuffer': true,
+  /** JSON response */
+  'json': true
 });
 
 /**
@@ -139,6 +145,14 @@ module.exports = function () {
    * @type {?String}
    */
   this._responseText = null;
+
+  /**
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/response
+   *
+   * @private
+   * @type {ArrayBuffer | String | Object}
+   */
+  this._response = null;
 };
 
 /** @alias module:node-http-xhr */
@@ -297,7 +311,15 @@ NodeHttpXHR.prototype = Object.create(
           throw new Error('Unsupported responseType "' + type + '"');
         }
 
-        return this._responseText;
+        switch (type) {
+        case '':
+        case 'text':
+          return this._responseText;
+        case 'arraybuffer':
+          return this._response;
+        default:
+          throw new Error('Assertion failed: unsupported response-type: ' + type);
+        }
       }
     },
     /**
@@ -308,10 +330,19 @@ NodeHttpXHR.prototype = Object.create(
      * This will be incomplete until the response actually finishes.
      *
      * @type {?String}
+     * @throws when `response` not a String
      * @readonly
      */
     responseText: {
-      get: function getResponseText() { return this._responseText; }
+      get: function getResponseText() {
+
+        // @see https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/responseText#Exceptions
+        if (this._responseType !== 'text' && this._responseType !== '') {
+          throw new Error('InvalidStateError: Response-type is ' + this._responseType);
+        }
+
+        return this._responseText;
+      }
     },
     /**
      * Indicates whether or not cross-site `Access-Control` requests should be
@@ -469,13 +500,35 @@ NodeHttpXHR.prototype.send = function (data) {
     this._resp = resp;
     this._responseText = '';
 
-    resp.setEncoding('utf8');
+    // var contentType = resp.headers['content-type'];
+    // TODO: adjust responseType from content-type header if applicable
+
+    // from Node API docs: The encoding argument is optional and only applies when chunk is a string. Defaults to 'utf8'.
+    if (this._responseType === 'text' || this._responseType === '') {
+      resp.setEncoding('utf8');
+    }
+
     resp.on('data', function onData(chunk) {
-      this._responseText += chunk;
+
+      if (typeof chunk === 'string') {
+        this._responseText += chunk;
+      } else if (typeof chunk === 'object') {
+        // binary data usually comes in one chunk (no chunky transfer-encoding)
+        // or at least, that's what we'll support here for now
+        if (chunk instanceof Buffer) {
+          this._response = chunk.buffer;
+        } else if (chunk instanceof ArrayBuffer) {
+          this._response = chunk;
+        } else {
+          // JSON case
+          this._response = chunk;
+        }
+      }
 
       if (this.readyState !== this.LOADING) {
         this._setReadyState(this.LOADING);
       }
+
     }.bind(this));
 
     resp.on('end', function onEnd() {