hey... i'm doing my html and javascript class project

and i want to have a msgbox welcoming the visitor asking for his name and then a welcoming msgbox shows up saying "hello (the name added)"

i know how to do that but my only problem is that if i pressed back and went to the homepage of my website again, the msg will show up again asking for my name

is there anyway to prevent this from happening? seriously don't want the visitor to wite his name each time he goes to the home page

please help

this is the code i'm using:

     <script> 
response = window.prompt("Welcome!","Please enter your name");


window.alert("hello " + response);




</script>

please help