Update and rename Nodejs Express.html to Nodejs Express.md

examples/Javascript Examples/Nodejs Express.md

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+## Generate Express project
+
+    npm install express-generator -g
+
+    express <name>        # Create boiler plate
+
+## Enabling CORS in Express
+
+To set CORS headers add an `app.use()` block like this
+
+    app.use(function (req, res, next) {
+        res.setHeader('Access-Control-Allow-Origin', 'http://server:8080');
+        res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
+        res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
+        res.setHeader('Access-Control-Allow-Credentials', true);
+        next();
+    });
+
+## Debugging Express Applications
+
+Ensure to install the 'debug' module
+
+    npm install debug
+
+And the run with debugging enabled by setting the DEBUG environment variable like this
+
+    DEBUG=express:* node index.js
+    DEBUG=http,mail,express:* node index.js
+
+    DEBUG=<app name>  node ./bin/www
+
+    DEBUG_FD=3 node index.js 3> logfile
+
+Debugging code would look like
+
+    d = debug('http:instance1');
+
+    d('Some logged event');
+    d('Another logged event');
+