---
title: Count substrings of string
type: snippet
language: javascript
tags: [string,algorithm]
author: chalarangelo
cover: obelisk
dateModified: 2021-01-08T00:23:44+02:00
---

Counts the occurrences of a substring in a given string.

- Use `Array.prototype.indexOf()` to look for `searchValue` in `str`.
- Increment a counter if the value is found and update the index, `i`.
- Use a `while` loop that will return as soon as the value returned from `Array.prototype.indexOf()` is `-1`.

```js
const countSubstrings = (str, searchValue) => {
  let count = 0,
    i = 0;
  while (true) {
    const r = str.indexOf(searchValue, i);
    if (r !== -1) [count, i] = [count + 1, r + 1];
    else return count;
  }
};
```

```js
countSubstrings('tiktok tok tok tik tok tik', 'tik'); // 3
countSubstrings('tutut tut tut', 'tut'); // 4
```