Differences between TypeScript and Flow


Facebook developed the Flow, which is a JavaScript static type checker that lives on top of our existing JS code. It is a flow-based typing tool, not a programming language. It does a lot of work to make us more productive. It makes our program faster, smarter, more confidently, and to a bigger scale.

Flow checks the code for errors using static type annotations. The type annotation allows us to tell Flow how we want our code to work, and Flow will make sure it does work the same way. The Flow is incrementally acceptable. It can be easily added and removed from our codebase without breaking anything. It is useful in situations when we want to enable type-checking for only one part of our project.


TypeScript is an open-source pure object-oriented programing language. It is a strongly typed superset of JavaScript which compiles to plain JavaScript. TypeScript is developed and maintained by Microsoft under the Apache 2 license. It is not directly run on the browser. It needs a compiler to compile and generate in JavaScript file. TypeScript source file is in ".ts" extension.

Anders Hejlsberg developed TypeScript. It was first introduced for the public in the month of 1 October 2012. After two years of internal development at Microsoft, the new version of TypeScript 0.9 was released in 2013. The current version of TypeScript is TypeScript 3.4.5 which was released on 24 April 2019.

TypeScript vs. Flow

We can understand the main differences between TypeScript and Flow from the below table.

TypeScript vs. Flow
TypeScript Flow
Introduction It is a typed superset of the JavaScript language. It is open-source and free programming language introduced by Microsoft. It is a flow-based typing tool, not a programming language. It is a JavaScript static type checker that lives on top of our existing JS code. Flow is built to enable fast and precise code analysis.
Design Goal It is used to identify errors in programs through a balance between correctness and productivity. It is used to enforce the type soundness/safety.
Use Case (popular frameworks integration) It becomes a better choice when we are working on Angular 2 or higher versions. If we are working on React, Flow becomes a better choice as it is easily integrated with babel and the already present infrastructure.
Benefits The key benefits are:
  • It uses static typing as a key benefit.
  • It provides useful tools such as code refactoring, auto-completion, navigation.
  • It has excellent IDE support.
  • It can easily integrate with VSCode, which made the editor so popular.
The key benefits are:
  • It uses static typing as a key benefit.
  • It provides a strong procedural analysis.
  • It can easily understand the code.
  • It strongly analyses and controls the program.
Features The main features of Typescript are:
  • Compile-time type checking
  • Type annotations
  • Type erasure
  • Type inference
  • Enumerated type
  • Interfaces
  • Namespaces
  • Generic
  • Tuples
The main features of Flow are:
  • Precision
  • Reliability
  • Speed
  • High throughput
  • Path sensitivity
  • Low latency
  • Type inference
  • Real-time feedback
  • Easy to integrate
  • Easily understandable JavaScript patterns
Services Along with the provision of static typing, it provides us with great language services and appropriate tooling that includes code refactoring, navigation, and auto-completion. Along with the provision of static typing, Flow provides us a wide range of inter-procedural analysis and develops an in-depth understanding of our code.
Advantages The advantages of TypeScript are:
  • Popular frameworks support (Vue, React, Angular)
  • Strong community
  • Strong IDE support
  • Compatibility with JavaScript
  • Declaration files
The advantages of Flow are:
  • Support for any JS file
  • Easy to integrate
  • Strong understanding of the JS patterns
  • Real-time feedback
  • Typecasting
  • Easy readability
  • Easier modification
Disadvantages The disadvantages of TypeScript are:
  • Another programming language
  • Harder to integrate with the existing JS projects
The disadvantages of Flow are:
  • Smaller community
  • Not so focused on the types
  • Smaller IDE support.
Utility size 42.4 MB 68.4 MB
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