includes method or we can use the
To use the
includes method, we can do that by writing the following code:
const hasFoo = 'foo bar'.includes('foo');
In the code above, we called the
includes method on the string literal. It takes the substring to seacrh for in the first argument.
The 2nd argument, which is optional, is the position in the string to start the search from.
true if the substring is found in the string that it’s called on and
In our example, we skipped the 2nd argument, so it’ll start searching from the beginning.
'foo' is in the string.
To search from a given index of the string that it’s called on, we can call it as follows:
const hasFoo = 'foo bar'.includes('foo', 5);
In the code above, it’ll start searching from index 5, which is past where
'foo' is. Therefore, it’ll return
indexOf is another method that we can use to check if a substring is in a string. It takes the same arguments as
includes but it returns the index of the first instance of the substring. If the substring isn’t found, then -1 is returned.
We can use it as follows:
const index = 'foo bar'.indexOf('foo');
We search for the
'foo' substring in the code above. Then
indexOf returns 0 since
'foo' is at the beginning of the string.
Also, we can set the index to start searching from as follows:
const index= 'foo bar'.indexOf('foo', 5);
Then we get -1 for
'foo' is not found in any index from 5 or beyond.
We can call