As software engineers, we all know that refactoring is important for maintaining and improving code quality. However, its very common being lazy.

Imagine a scenario where, during a code review, someone identifies a code smell and suggests some changes. You might respond by saying there's no time for that now and that we'll add it to our technical debt backlog. Or perhaps you leave a few TODO comments instead of taking the time to write clean code. It’ll get done eventually, right?
No! In reality, these tasks rarely get completed once they’re consigned to the limbo of “to be done later.” There's always something more urgent than refactoring.

In this post, we'll explore some tips for deciding the best time to refactor and how to do it in a legacy codebase.

Best Time to Refactor

Refactoring is a continuous process that should be done throughout the development cycle. So, if I had to answer that in one word that would be NOW. Pretty explicit from the cover!

"Its always the best time to refactor"!

However, there are certain times when you will find the opportunity to do refactoring.

1. When Adding New Features

Adding new features to an existing code base can be a good opportunity to refactor. Refactoring before adding new features can help to reduce the technical debt and improve the overall quality of the codebase. It's easier to refactor before adding new features than after.

2. When Fixing Bugs

Fixing bugs can also be a good time to refactor. If a bug is caused by poorly written code, refactoring can help to prevent similar bugs from happening in the future. Refactoring while fixing bugs can also make the code easier to understand and maintain.

3. When Working on Code That's Already Being Touched

If you're already working on a specific section of the codebase and you feel a room for improvement, it can be a good opportunity to refactor that section as well. This can help to improve the quality of the codebase and reduce technical debt.

Refactoring in a Legacy Code Base

Refactoring in a legacy code base can be challenging. Legacy codebases are often large, complex, and poorly documented, making it difficult to understand the code's behavior and dependencies. Here are some tips for refactoring a legacy code base:

1. Understand the Code

Before you start refactoring, it's essential to understand the codebase's structure and behavior. This includes understanding how different components interact with each other, identifying areas of the codebase that are prone to errors, and determining the code's overall complexity.

2. Identify Code Smells

Identifying code smells is crucial for effective refactoring in a legacy codebase. Common code smells include duplicated code, long methods, and excessive nesting. Identifying these code smells can help you prioritize which sections of the codebase need to be refactored.

3. Start Small

Refactoring a legacy code base can be overwhelming, so it's essential to start small. Identify small sections of the codebase that can be refactored without impacting the rest of the codebase's behavior. Starting small can help you build momentum and reduce the risk of breaking the codebase.

4. Write Tests

Writing tests can have a significant impact on refactoring and it help you to ensure that your refactoring efforts don't introduce new bugs or break existing functionality. Tests can also serve as documentation for the codebase, making it easier to understand and maintain in the future.

5. Refactor Incrementally

Refactoring a legacy codebase can be a time-consuming process, so it's essential to do it incrementally. Refactor small sections of the codebase at a time, and make sure that the code still works as expected after each change.

Practical Example: Refactoring with Ag-Grid and Formik

In one of my projects, we used Ag-Grid for an enterprise application to display large amounts of data, hierarchies, and computations, making it highly customizable and extensible. We had numerous computations on the grids and were using Formik for managing the state of the grid as a form.

Working with a legacy codebase, we faced the need to incorporate enterprise features from newer versions of both Ag-Grid and Formik which had a lot of performance improvements. However, directly updating these libraries was not feasible due to significant breaking changes.

To address this challenge, we adopted an incremental approach:

1. Initial Setup: We installed the latest versions of Ag-Grid and Formik alongside the existing versions. This allowed us to experiment without disrupting the current functionality.

2. Starting Small: We began by updating a small, manageable section of the application. This section was chosen for its simplicity and minimal dependencies, reducing the risk of introducing errors.

3. Creating a Reference Implementation: Successfully updating this small section provided us with a reference implementation. This served as a guide for how to handle similar updates throughout the codebase.

4. Gradual Rollout: Using the reference implementation, we incrementally updated other sections of the application. This step-by-step approach minimized risks and allowed for continuous testing and verification.

5. Comprehensive Testing: Throughout the process, we ensured thorough testing at each stage. Writing and running tests helped us catch and fix issues early, maintaining the stability of the application.

This methodical and incremental strategy enabled us to modernize the codebase effectively. By breaking the task into smaller, manageable pieces, we were able to mitigate risks, ensure compatibility, and gradually leverage the new features offered by the updated libraries.

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I would love to hear from you guys on the following:_

1. What's the most challenging refactoring you've tackled, and how did you approach it?
2. How do you prioritize refactoring in your development workflow?
3. What are your favorite refactoring techniques or tools, and why?
4. Have you ever faced resistance to refactoring within your team or organization? How did you overcome it?
5. How do you balance the trade-off between refactoring for maintainability and delivering new features quickly?