[Javascript] I can test for undefined...using typeof or === or == please help

[Scott.Wiseman]

non of these if statements catch the undefined
 
but the alert reports 0 undefined.
so what's up.... is there a type???
 
 
here is the code:
 
 
 alert("0 "+mydropdown.options[0].value);
   if(typeof mydropdown.options[0].value == undefined)
   {
    alert("found 1")
    myvalue1 = NULL;
   }
   if(typeof mydropdown.options[0].value == undefined)
   {
    alert("found x 1")
   }
   if(typeof mydropdown.options[0].value === undefined)
   {
    alert("found x 2")
   }
   if(mydropdown.options[0].value == undefined)
   {
    alert("found x 3")
   }
 
   if(typeof mydropdown.options[0].value != undefined ||
mydropdown.options[0].value != "unde" )
   {
    myvalue1 = mydropdown.options[0].value;
   }
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