To blink the on board LED from a web browser, save the code below as htmlblink.js and from the command line run

# node htmlblink.js

Then point your browser to your device on port 8081
e.g. http://Omega-ABCD:8081

var http = require('http');
var fs = require('fs');

var ledFle = '/sys/class/leds/onion\:amber\:system/brightness';

function led(onOff) {
 fs.writeFile( ledFle, onOff, function(err){
  if (err) {
   return console.log(err);
  }
 });
}

function handleRequest(req,res) {
 if (req.url=='/ledon') {
  led(1);
 }
 if (req.url=='/ledoff') {
  led(0);
 }
 res.writeHead(200, { "Content-Type": "text/html" });
 res.write("<h1>LED SWITCH</h1>");
 res.write('<a href="/ledon">[ON]</a> | <a href="/ledoff">[OFF]</a> ');
 res.end();
}

var server = http.createServer(handleRequest);

server.listen(8081, function(){
 console.log("listening for http on port 8081");
});