asp to javascript

[fromhell]

hye all, i'm new with javascript thing
can someone show me how to convert the asp code (given below) to javascript..

please help me



Function getID(instring)
if instr(instring,"light") or instr(instring,"lite") then
getID=7
elseif instr(instring,"mix") then
getID=8

[fromhell]

i want this script to get an instring value and match it..and after that assign an id to getID...

i try to write the code to this, but i just got an 'undefined' messagebox

function getID(instring)
{

if (instring.match("era"))
{
getID=8;
}

}

alert(getID("era"))

</script>