Feature: Add request hooks

karma.conf.js

@@ -11,7 +11,7 @@ module.exports = function(config) {
 
     // frameworks to use
     // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
-    frameworks: ['mocha', 'chai'],
+    frameworks: ['jasmine'],
 
 
     // list of files / patterns to load in the browser

package.json

@@ -34,18 +34,17 @@
   "devDependencies": {
     "@babel/core": "^7.1.0",
     "@babel/preset-env": "^7.1.0",
-    "chai": "^4.1.2",
     "eslint": "^5.16.0",
     "eslint-config-airbnb-base": "^13.1.0",
     "eslint-plugin-import": "^2.16.0",
     "karma": "^4.2.0",
     "karma-chai": "^0.1.0",
     "karma-chrome-launcher": "^2.2.0",
-    "karma-mocha": "^1.3.0",
-    "mocha": "^5.2.0",
+    "karma-jasmine": "^4.0.1",
     "prettier": "^1.16.4",
     "puppeteer": "^1.18.1",
     "rollup": "^0.63.2",
     "rollup-plugin-babel": "^4.0.3"
-  }
+  },
+  "dependencies": {}
 }

src/api.js

@@ -26,6 +26,15 @@ const MEDIATYPES = {
   PNG: "image/png"
 };
 
+/**
+ * A callback with the request instance and metadata information
+ * of the currently request being executed that should necessarily
+ * return the given request optionally modified.
+ * @typedef {function} RequestInterceptor
+ * @param {XMLHttpRequest} request - The original XMLHttpRequest instance.
+ * @param {object} metadata - The metadata used by the request.
+ */
+
 /**
  * Class for interacting with DICOMweb RESTful services.
  */
@@ -37,6 +46,7 @@ class DICOMwebClient {
    * @param {String} options.username - Username
    * @param {String} options.password - Password
    * @param {Object} options.headers - HTTP headers
+   * @param {Array.<RequestInterceptor>} options.requestInterceptors - Request interceptors.
    */
   constructor(options) {
     this.baseURL = options.url;
@@ -75,6 +85,10 @@ class DICOMwebClient {
       this.stowURL = this.baseURL;
     }
 
+    if ("requestInterceptors" in options) {
+      this.requestInterceptors = options.requestInterceptors;
+    }
+
     // Headers to pass to requests.
     this.headers = options.headers || {};
 
@@ -100,15 +114,16 @@ class DICOMwebClient {
    * @param {String} method
    * @param {Object} headers
    * @param {Object} options
+   * @param {Array.<RequestInterceptor>} options.requestInterceptors - Request interceptors.
    * @return {*}
    * @private
    */
   _httpRequest(url, method, headers, options = {}) {
 
-    const {errorInterceptor} = this;
+    const { errorInterceptor, requestInterceptors } = this;
 
     return new Promise((resolve, reject) => {
-      const request = new XMLHttpRequest();
+      let request = new XMLHttpRequest();
       request.open(method, url, true);
       if ("responseType" in options) {
         request.responseType = options.responseType;
@@ -171,6 +186,14 @@ class DICOMwebClient {
         }
       }
 
+      if (requestInterceptors) { 
+        console.debug('yes')
+        const metadata = { method, url };
+        const pipeRequestInterceptors = functions => (args) => functions.reduce((args, fn) => fn(args, metadata), args);
+        const pipedRequest = pipeRequestInterceptors(requestInterceptors);
+        request = pipedRequest(request);
+      }
+
       if ("data" in options) {
         request.send(options.data);
       } else {
@@ -190,9 +213,9 @@ class DICOMwebClient {
    * @private
    */
   _httpGet(url, headers, responseType, progressCallback) {
-    return this._httpRequest(url, "get", headers, {
-      responseType,
-      progressCallback
+    return this._httpRequest(url, "get", headers, { 
+      responseType, 
+      progressCallback 
     });
   }
 
@@ -629,9 +652,9 @@ class DICOMwebClient {
    * @returns {Promise} Response
    */
   _httpPost(url, headers, data, progressCallback) {
-    return this._httpRequest(url, "post", headers, {
-      data,
-      progressCallback
+    return this._httpRequest(url, "post", headers, { 
+      data, 
+      progressCallback 
     });
   }