The browser storage localStorage is not available. Either your browser does not support it or you have disabled it or the maximum memory size is exceeded. Without localStorage your solutions will not be stored.

String: indexOf() with from index

The indexOf method allows you to specify the position from which the search should start. This is done with a second parameter.

let n1 = 'White Rabbit'.indexOf('it', 1);
let n2 = 'White Rabbit'.indexOf('it', 3);

The first 'it' in 'White Rabbit' has the index 2. Starting our search at position 1 it will be found. n1 is 2. The second 'it' in 'White Rabbit' has the index 10. Starting our search at position 3 it will be found. n2 is 10.

Exercise

Write a function secondIndexOf, taking two strings and determining the second occurrence of the second string in the first string. If the search string does not occur twice, -1 should be returned.

Example: secondIndexOf('White Rabbit', 'it') should return 10.

+ Hint

function secondIndexOf(s1, s2) {
// Use indexOf twice.
}

+ Solution

function secondIndexOf(s1, s2) {
  let firstIndex = s1.indexOf(s2);
  return s1.indexOf(s2, firstIndex + 1);
}