How to Count String Occurrence in String?

How to Count String Occurrence in a String?

When working with JavaScript, it is common to come across situations where you need to count the occurrence of a specific string within another string. This can be useful for various purposes, such as analyzing user input or extracting data from a larger text. In this blog post, we will explore different approaches to count string occurrences in JavaScript.

Method 1: Using the match() method

The match() method in JavaScript can be used to find all occurrences of a pattern within a string. By providing a regular expression as an argument, we can count the number of matches found. Here’s an example:

const str = "Hello, hello, hello!";
const searchStr = "hello";
const regex = new RegExp(searchStr, "gi");
const count = (str.match(regex) || []).length;

console.log(count); // Output: 3

In the above code snippet, we define the string str and the search string searchStr. We create a regular expression using the search string and the RegExp constructor, with the gi flags to perform a case-insensitive and global search. We then use the match() method to find all matches and store them in an array. Finally, we use the length property to get the count of matches.

Method 2: Using the split() method

Another approach to count string occurrences is by splitting the string into an array based on the search string and then getting the length of the resulting array. Here’s an example:

const str = "Hello, hello, hello!";
const searchStr = "hello";
const count = str.split(searchStr).length - 1;

console.log(count); // Output: 3

In the above code snippet, we use the split() method to split the string str into an array based on the search string searchStr. We then subtract 1 from the length of the resulting array to get the count of occurrences.

Method 3: Using a loop

If you prefer a more traditional approach, you can use a loop to iterate over the string and count the occurrences manually. Here’s an example:

const str = "Hello, hello, hello!";
const searchStr = "hello";
let count = 0;
let index = str.indexOf(searchStr);

while (index !== -1) {
  count++;
  index = str.indexOf(searchStr, index + 1);
}

console.log(count); // Output: 3

In the above code snippet, we initialize the count to 0 and the index to the first occurrence of the search string using the indexOf() method. We then enter a loop that increments the count and updates the index to the next occurrence until no more occurrences are found.

These are three different methods you can use to count string occurrences in JavaScript. Choose the one that best suits your needs and implement it accordingly. Happy coding!