Returns an integer value one higher than the highest element defined in an array.
As the elements in an array do not have to be contiguous, the length property is not necessarily the number of elements in the array. For example, in the following array definition, my_array.length contains 7, not 2:
If a value smaller than its previous value is assigned to the length property, the array is truncated, and any elements with array indexes equal to or greater than the new value of the length property are lost.
If a value larger than its previous value is assigned to the length property, the array is expanded, and any new elements created have the value undefined.
The following example illustrates the use of the length property: