TypeScript + React

An in depth look

The appeal of TypeScript + React 

It all comes down to static typing.

TypeScript is just JavaScript  -  just with the seat belt fastened.

Static typing advantages

• working with large code bases is hard in general
• when using a dynamic language, it takes more discipline
  • naming and other conventions
• this is how linters were born
  • but TS is not a replacement for a linter, there is `tslint`
• catches a class of easy to make, but hard to find bugs
  • spelling errors for instance
• enables smarter tooling
  • refactoring is not find in files anymore
• the code is self documenting

About TypeScript

• created by M$ Microsoft in 2012
• created by Anders Hejlsberg
• open source from the beginning, hosted on github
• follows ES spec closely
• quite open and inclusive, adopted by Angular2 and Dojo2
• has great IDE support

TypeScript cool features

• interfaces
• generics
• enums
• advanced types
• method access modifiers

Compiler related:

• type definiton files
• bundles normal JS files

Interfaces

• anonymous interfaces
• can describe function types
• can extend a class
• can be generic

Advanced types

• union types
• type guards
  • typeof
  • instanceof
• intersection types
• type aliases (can be generic)
• string literal types

React with TypeScript

• React has 1st class support in TS
  • TS compiler has support for React since v 1.6 (sept 2015)
  • TS compiler can transpile the JSX code to JavaScript
  • new React fixes with every new TS release
• interfaces for props and state
• component attribute checks
  • is modeled after how JSX is transformed
• no need for prop types
• works with the usual tools: webpack
• TypeScript 1.8
  • supports stateless function components
  • simplified props type management

Tips, tricks and gotchas

• lazy object initialization
• calling setState() with less keys
• missing type definition files
  • provide a dummy definition
  • write a proper .d.ts file (starting from the API doc)

TS compared to Flow

There is a bit of overlap.

TypeScript advantages:

• wider adoption, more mature, great tool support
• more features: enums, union types
• lots of type definition files
• Flow doesn't work on Windows

Flow advantages:

• incredibly smooth transition
• super fast

Advices

• use tslint and try to be as strict as possible
• try to avoid any as it defies the purpose of TS
• use the class construct for organizing the code
• always prefer composition to inheritance
  • specially with React
• try to follow the TypeScript coding standards
  • https://github.com/Microsoft/TypeScript/wiki/Coding-guidelines

End