I would like to write a Javascript which allows me to dynamically populate the contents of a simple HTML drop-down menu when certain elements of another drop-down menu are selected, without having to reload the page. At the moment, the user has to select an element of the first menu, press a 'submit' button, which then reloads the page and causes the second menu to be populated accordingly. However, I would like the second menu's contents to be update as soon as the user selectes an element of the first menu. To illustrate what I mean, please take a look at the Javascript menu system on the following page : http://www.easyjet.com/en/ When you click on a departure airport, the contents of the arrival airport menu a   More>>