Question

I am receiving a html form. This works fine when 2 or more elements in array, but when only one element is received I get error users[t] is null in fireBug?

var users = form.elements["uname[]"];

for(t in users) {
  dataString += "User: "+users[t].value+"\n"
}

this solved it:

if( typeof users.value === 'string' ) {
   users = [ users ];
}

Answer 1

You could check if the variable is a string and convert it to an array:

if( typeof users === 'string' ) {
    users = [ users ];
}

For iterating arrays for-in should be avoided, that statement is meant to enumerate object properties. You could try using a better loop, something like:

var userCount = users.length;
for (var i = 0; i < userCount; i++) {
      dataString += "User: "+users[i].value+"\n"
}

You could also base a test on the length. If the object is single it will return undefined for length.

var userCount = users.length; //Get user count
if ( userCount == undefined ) { //Returned undefined if not an array.
    users = [ users ]; //Convert to array
}