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Learn how to count occurrences of a specific substring in a string and replace it with that substring alongside its count using JavaScript.
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Counting String Occurrences and Replacing Them with a Count in JavaScript

In the world of programming, it’s quite common to handle strings and manipulate them based on certain criteria. One common challenge developers face is counting the occurrences of a specific substring within a larger string and replacing it in a formatted way when certain conditions are met. In this guide, we'll address a specific scenario: counting occurrences of the substring "transfer" in a given string and replacing it with that substring followed by the count if it appears consecutively.

The Problem

Imagine you have a string that may contain the word “transfer” multiple times, in various cases, and you want to achieve the following:

If "transfer" appears continuously (i.e., consecutively), you'd want to replace it with "transfer" followed by the count of its occurrences.

If it appears in a non-consecutive manner, you'd return the string unmodified.

The function should be case insensitive, meaning "Transfer", "TRANSFER", and "transfer" should all be recognized as the same.

Examples

Here are a few examples based on the given requirements:

Input: 'Name transfer transfer transfer transfertransfer'
Output: 'Name transfer 5'

Input: 'Name transfer Transfer transfer TransferTranfser'
Output: 'Name transfer 5'

Input: 'Name transfer name transfer'
Output: 'Name transfer name transfer'

The Solution

To achieve this, we can leverage JavaScript's regular expressions along with its string manipulation methods. Below is a breakdown of the solution approach:

Step 1: Define the String

First, we define the original string we want to manipulate.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Count Occurrences

Using a regular expression, we count the occurrences of "transfer" in a case insensitive manner.

[[See Video to Reveal this Text or Code Snippet]]

Where:

/transfer/ig is the regex pattern used to find all occurrences of "transfer". The i flag makes it case insensitive, and the g flag allows it to match globally across the string.

Step 3: Check Count

Next, we determine if the count of occurrences is greater than 1.

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Replace with Count

If "transfer" occurs more than once, we want to replace it across the string. Here’s how to do that while also ensuring any trailing spaces are managed:

[[See Video to Reveal this Text or Code Snippet]]

This line:

Uses replace to remove all instances of "transfer" while ensuring spaces around them are also removed.

Then it appends the formatted string with the count.

Step 5: Output the Results

Finally, we can log the count and the modified string:

[[See Video to Reveal this Text or Code Snippet]]

Complete Code

Here’s the complete solution encapsulated in a simple JavaScript code block:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you can easily count and replace substrings in JavaScript to fit specific requirements. This kind of functionality is invaluable for string manipulation in web applications, enhancing both user experience and data presentation.

Feel free to adapt the logic for other substrings or different conditions, and happy coding!