[FINoM]

var Iterator = function( array ) { 
 this.array = array;
 this.index = -1;
 this.iterate = function() {
  return this.array[ ++this.index ] || this.array[ this.index = 0 ] 
 }
}
var iterator = new Iterator(['a', 'b', 'c', 'd', 'e']);
alert([iterator.iterate(),  iterator.iterate(),  iterator.iterate(),  iterator.iterate(),  iterator.iterate(),  iterator.iterate(),  iterator.iterate()]);