Javascript decision making
You
If and If/else
More information: http://www.w3schools.com/js/js_if_else.asp
Switch/case
More information here: http://www.w3schools.com/js/js_switch.asp
For the assignment you need to explain how javascript cannot really be hidden and that scripts placed on other websites are readily available to be copied. Try to find a script on another site and put it in your site to explain.