The lastIndexOf() method helps us locate
the last instance of a substring
inside a string.
It accepts two arguments -
substring
and
fromIndex.
The method returns index of the
the first occurrence of the substring
by searching the main string from
it's last index to its first.
In other words,
the method returns the index of the
last occurrence of the substring.
The default value of fromIndex is
the last index of the string.
Let's take a look at an example
that passes only the substring argument.
In the example given above,
the last occurrence of "es",
inside "Sam loves mangoes."
is at the index 15
and
hence the output is 15.
In the example given above,
the method looks for the substring
from the index 9 and below.
In other words,
it looks for the substring
inside "Sam loves ".
In this case,
the last occurrence of "es"
is at the index 7.
If there are no matches,
the method would return -1.
In the above example,
there were no occurrences of "xy"
inside "Sam loves mangoes."
and so we go the output as -1.