The syntax of indexOf method is as below :
str.indexOf(subStr [, startIndex])
It takes two parameters, one is optional.
subStr : This is the sub string to find in the string str.
startIndex : This is an optional integer value to define the start index from where the search should begin. By default, it’s value is 0 i.e. the search starts from the first character of the string.
Return value :
Let’s take a look at the example below :
let str = "The quick brown fox jumps over the lazy dog"; //1 console.log(str.indexOf("The")); //2 console.log(str.indexOf("the")); //3 console.log(str.indexOf("h")); //4 console.log(str.indexOf("h",5)); //5 console.log(str.indexOf("hello"));
0 31 1 32 -1
In this example :
1. The first console.log statement prints 0 because the first occurrence of ‘The’ is at index 0 in the string.
2. The second console.log statement prints 31 because the first occurrence of ‘the’ is at index 31 in the string.
3. The first occurrence of ‘h’ is at index 1.
4. The first occurrence of ‘h’ is at index 32 if the search starts at index 5 .
5. The substring ‘hello’ is not available in the given string. So, it prints -1 .