Returns the last occurrence of a substring within a String object.
The lastIndexOf method returns an integer value indicating the beginning of the substring within the String object. If the substring is not found, a -1 is returned.
If startindex is negative, startindex is treated as zero. If it is larger than the greatest character position index, it is treated as the largest possible index.
Searching is performed right to left. Otherwise, this method is identical to indexOf.
The following example illustrates the use of the lastIndexOf method.