All browsers support “View page source” feature. But what it displays is source of the page as it was originally rendered by the server. In today’s Web 2.0 world page content can change a thousand times after that. Client-side script, user input, AJAX calls can contribute to page update.
But one line of JavaScript code can show you a real up-to date page source. Type following in your browser address bar:
javascript:void prompt('HTML Source',document.documentElement.innerHTML)