benjamingr · January 15, 2019 20:18 · Jan 15, 2019
diff --git a/intercept-network-requests.js b/intercept-network-requests.js
@@ -0,0 +1,69 @@
+function interceptNetworkRequests(ee) {
+    const open = XMLHttpRequest.prototype.open;
+    const send = XMLHttpRequest.prototype.send;
+
+    const isRegularXHR = open.toString().indexOf('native code') !== -1;
+
+
+    // don't hijack if already hijacked - this will mess up with frameworks like Angular with zones
+    // we work if we load first there which we can.
+    if (isRegularXHR) {
+        XMLHttpRequest.prototype.open = function() {
+            ee.onOpen && ee.onOpen(this, arguments);
+            if (ee.onLoad) {
+                this.addEventListener('load', ee.onLoad.bind(ee));
+            }
+            if (ee.onError) {
+                this.addEventListener('error', ee.onError.bind(ee));
+            }
+            return open.apply(this, arguments);
+        };
+        XMLHttpRequest.prototype.send = function() {
+            ee.onSend && ee.onSend(this, arguments);
+            return send.apply(this, arguments);
+        };
+    }
+
+    const fetch = window.fetch || "";
+    // don't hijack twice, if fetch is built with XHR no need to decorate, if already hijacked
+    // then this is dangerous and we opt out
+    const isFetchNative = fetch.toString().indexOf('native code') !== -1;
+    if(isFetchNative) {
+        window.fetch = function () {
+            ee.onFetch && ee.onFetch(arguments);
+            const p = fetch.apply(this, arguments);
+            p.then(ee.onFetchResponse, ee.onFetchError);
+            return p;
+        };
+        // at the moment, we don't listen to streams which are likely video 
+        const json = Response.prototype.json;
+        const text = Response.prototype.text;
+        const blob = Response.prototype.blob;
+        Response.prototype.json = function () {
+            const p = json.apply(this.arguments);
+            p.then(ee.onFetchLoad && ee.onFetchLoad.bind(ee, "json"));
+            return p;
+        };
+        Response.prototype.text = function () {
+            const p = text.apply(this.arguments);
+            p.then(ee.onFetchLoad && ee.onFetchLoad.bind(ee, "text"));
+            return p;
+        };
+        Response.prototype.blob = function () {
+            const p = blob.apply(this.arguments);
+            p.then(ee.onFetchLoad && ee.onFetchLoad.bind(ee, "blob"));
+            return p;
+        };
+    }
+    return ee;
+}
+
+interceptNetworkRequests({
+    onFetch: console.log,
+    onFetchResponse: console.log,
+    onFetchLoad: console.log,    
+    onOpen: console.log,
+    onSend: console.log,
+    onError: console.log,
+    onLoad: console.log
+});