babel-plugin-flow-to-typescript

[Babel] plugin to convert [Flow] code into [TypeScript]

How to use

``shell
$ npm install -g @babel/cli @babel/core
$ npm install babel-plugin-flow-to-typescript

you must use babel@^7.x.x

$ babel --plugins babel-plugin-flow-to-typescript ${SRC_FLOW_FILE} -o ${DEST_TS_FILE}
`

Implementation status

| Supported? | Syntax | Flow | TypeScript |
| ---------- | --------------------- | --------------------------------- | ----------------------------------------------- |
| ✅ | Maybe type | let a:?number | let a: number \| null \| undefined |
| ✅ | Void type | void | void |
| ✅ | Object type | Object | object |
| ✅ | Mixed type | mixed | unknown |
| ✅ | Function type | (A, B) => C | (x1: A, x2: B) => C |
| ✅ | Exact type | {\| a: A \|} | { a: A } |
| ✅ | Indexers | { [A]: B } | { [a: A]: B } |
| ✅ | Existential type | Map<, > | Map |
| ✅ | Opaque types | opaque type A = B | type A = B |
| ✅ | Variance | interface A { +b: B, -c: C } | interface A { readonly b: B, c: C } |
| ✅ | Type parameter bounds | function f(a:A){} | function f(a:A){} |
| ✅ | Cast | (a: A) | (a as A) |
| ✅ | type/typeof import | import type A from 'module' | import A from 'module' |
| ✅ | \$Keys | $Keys | keyof X |
| ✅ | \$Values | $Values | X[keyof X] |
| ✅ | \$ReadOnly | $Readonly | Readonly |
| ✅ | \$Exact | $Exact | X |
| ✅ | \$Diff | $Diff | Pick> |
| ✅ | \$PropertyType | $PropertyType | T[k] |
| ✅ | \$ElementType | $ElementType | T[k] |
| ✅ | $Shape | $Shape | Partial |
| ✅ | Class | Class | typeof T |
| ✅ | typeof operator | typeof foo | typeof foo |
| ✅ | JSX | - | - |
| ✅ | Tuple type | [number, string] | [number, string] |
| ✅ | Type alias | type A = string | type A = string |
| ✅ | Flow Ignore | $FlowFixMe | any |
| ✅ | Interfaces | interface X { +prop: string } | interface X { readonly prop: string } |
| ✅ | Optional Members | a?.b | ... |
| ✅ | Declare functions | declare function x(false): true;| function x(x0: false): true; |
| ✅ | Declare Class | ... | ...` |

[babel]: https://github.com/babel/babel
[flow]: https://github.com/facebook/flow
[typescript]: https://github.com/Microsoft/TypeScript