adding post-processing example

Author: jkyberneees

demos/post-processing.js

@@ -0,0 +1,31 @@
+const toArray = require('stream-to-array')
+const gateway = require('../index')
+
+gateway({
+  routes: [{
+    prefix: '/httpbin',
+    target: 'https://httpbin.org',
+    hooks: {
+      async onResponse (req, res, stream) {
+        // collect all streams parts
+        const resBuffer = Buffer.concat(await toArray(stream))
+
+        // parse response body, for example: JSON
+        const payload = JSON.parse(resBuffer)
+        // modify the response, for example adding new properties
+        payload.newProperty = 'post-processing'
+
+        // stringify response object again
+        const newResponseBody = JSON.stringify(payload)
+
+        // set new content-length header
+        res.setHeader('content-length', '' + Buffer.byteLength(newResponseBody))
+        // set response statusCode
+        res.statusCode = stream.statusCode
+
+        // send new response payload
+        res.end(newResponseBody)
+      }
+    }
+  }]
+}).start(8080)