Should You Use Strict Mode in TypeScript?

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TypeScript is a superset of JavaScript that adds static types to the language. It allows developers to catch errors during development rather than at runtime, leading to more reliable and maintainable code. One of the key features of TypeScript is “strict mode,” which enforces stricter type checking rules. In this article, we’ll explore the benefits and potential drawbacks of using strict mode in TypeScript to help you decide if it’s the right choice for your projects.

What is Strict Mode in TypeScript?

Strict mode in TypeScript enables a set of stricter type checking rules. When strict mode is enabled, TypeScript will catch more potential errors during development, helping you write safer and more predictable code.

The strict mode encompasses several individual settings, including:

  1. noImplicitAny: Disallows the use of variables and function parameters with an implicit any type.
  2. strictNullChecks: Null and undefined values are not automatically assignable to all types.
  3. strictFunctionTypes: Function parameter types must match exactly.
  4. strictPropertyInitialization: Class properties must be initialized in the constructor.
  5. strictBindCallApply: bind, call, and apply methods on functions are stricter.

Advantages of Using Strict Mode

1. Early Error Detection

One of the primary benefits of using strict mode is that it helps catch errors early in the development process. TypeScript will identify potential issues before your code ever reaches the runtime environment. This leads to a more robust codebase and reduces the likelihood of runtime errors.

2. Improved Code Quality

With strict mode enabled, TypeScript encourages you to write cleaner, more reliable code. You’re forced to be explicit about types, which can lead to better documentation and easier code maintenance. This is particularly valuable in larger projects with multiple contributors.

3. Enhanced Refactoring

The strict mode helps with code refactoring. When you make changes to your code, TypeScript provides more accurate feedback on how those changes impact the rest of your application. This can save a significant amount of time in the long run.

4. Better Collaboration

In a team setting, strict mode can be a game-changer. It provides a shared understanding of the codebase and reduces misunderstandings among team members. It also encourages consistent coding practices, making it easier for developers to work on each other’s code.

Potential Drawbacks of Using Strict Mode

1. Learning Curve

For developers new to TypeScript, strict mode can be initially challenging. It requires a deeper understanding of the language’s type system. However, once the concepts are grasped, it leads to more efficient and reliable code.

2. Potential Overhead

In some cases, strict mode may require additional time during the development process. Writing explicit types and adhering to stricter rules can be perceived as more time-consuming. However, this investment often pays off in terms of reduced debugging time and improved code quality.

3. Legacy Code Integration

If you’re introducing TypeScript into an existing codebase, enabling strict mode may require significant refactoring. This can be a time-consuming process, especially if the code was not originally written with strong typing in mind.

When to Use Strict Mode

Strict mode in TypeScript is highly recommended for new projects. It provides a solid foundation for building reliable and maintainable code. Additionally, if you’re working on a team project, strict mode can be invaluable for ensuring consistency and reducing potential sources of bugs.

For existing projects, introducing strict mode can be a more gradual process. You might start by enabling specific strict checks one at a time and addressing any resulting errors. This allows you to incrementally adopt stricter type checking without the need for a massive refactor.


In conclusion, using strict mode in TypeScript offers significant benefits in terms of early error detection, improved code quality, enhanced refactoring, and better collaboration. While there may be a learning curve and potential overhead, the long-term advantages outweigh the initial investment.

For new projects or projects with a team of developers, enabling strict mode from the outset is highly recommended. For existing projects, consider a phased approach to gradually introduce strict mode and reap the benefits of more robust and maintainable code.

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Rajae Robinson

Rajae Robinson is a young Software Developer with over 3 years of work experience building websites and mobile apps. He has extensive experience with React.js and Next.js.

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