title: Display alert message in browser using Node.js
body: <p>I need to display an alert message in browser using Node.js code. Here my code</p>
  
  <pre><code>app.post('/logon', function (req, res)
     {
        var user=req.body.userName;
        var password=req.body.password;
        if((user=='admin')&amp;&amp;(password=='admin'))
           { 
                //redirect to home page
            }
         else
            {
                  //here I need to display a alert message in browser saying that invalid user name or password is wrong
             }
         ..........
  </code></pre>