How to Count Substrings in a String using JavaScript
If you want to practice coding, open the Terminal/SSH and type node
. This JavaScript function counts the number of occurrences of a specified substring in a given string.
To use this function, follow these steps:
- Declare a function called
countSubstrings
that takes two parameters: str
and searchValue
.
- Initialize two variables:
count
and i
.
- Use the
Array.prototype.indexOf()
method to search for searchValue
in str
.
- If the value is found, increment the
count
variable and update the i
variable.
- Use a
while
loop that returns as soon as the value returned from Array.prototype.indexOf()
is -1
.
- Return the
count
variable.
Here's the code for the countSubstrings
function:
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;
}
};
You can test the function using the examples below:
countSubstrings("tiktok tok tok tik tok tik", "tik"); // 3
countSubstrings("tutut tut tut", "tut"); // 4