There are a couple of ways in which
we can find if a string contains
another string or substring.
The indexOf() method helps us
locate a substring inside a string.
The method accepts two arguments -
substring
and
fromIndex.
The default value of fromIndex
is 0.
Let's take a look at an example,
where we pass only the substring.
In the example given above,
the first occurrence of "es",
inside "Sam loves mangoes."
is at the index 7
and
hence the output is 7.
Now let's take a look at an example,
where we pass both the substring
and
fromIndex arguments.
In the example given above,
the method looks for the substring
from the index 9.
In other words,
it looks for the substring
inside " mangoes."
In this case,
the first occurrence of "es"
is at the index 15.
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.