I adapted the following code from here:

HTML:

1. <button class="btn" name="btnAddlEmail" id="btnAddlEmail">Add Another Email</button>

Javascript:

1. $("#btnAddlEmail").click(function () {
                   var email = prompt('Please enter the email address', ' name@provider.com');
                   if (email != null) //&& (email != " name@provider.com")
                   {
                       alert(email);
                   }
               }); 

...but it's not working; I thought maybe it was some unrelated problem that was causing it not to work, but 

even this simplistic fiddle doesn't prompt when the button is clicked:

What am I doing wrong in my Javascript?