flow-upgrade

A utility for upgrading your codebase to the latest version of Flow.

Install using yarn add flow-upgrade. We expect prettier to be installed as a peer dependency wherever you are running flow-upgrade.

You can then run:

``
yarn run flow-upgrade
`

You may also use npx:

`
npx flow-upgrade
`

We also supply the flow-codemod binary:

`
yarn run flow-codemod
`

If you just want to run a codemod without specifying Flow versions.

Options

$3

By default, Flow will only upgrade files that have an // @flow header comment.
If you want to upgrade all of your JavaScript files you may pass in the --all:

`
yarn create flow-upgrade --all
`

$3

Path to a .prettierrc file to use.
Upgrade codemods rely upon prettier to print the resulting code after transformation.
If this is not provided, we will just use the defaults.

Codemods available

$3


Converts static object assignments (e.g. const o = {}; o.a = 1;) to inline properties (e.g. const o = {a: 1};).

Run with yarn run flow-codemod collapseObjectInitialization.

$3


Replaces T: {} with T: {...} in type parameter bounds. The former is almost always wrong.

Run with yarn run flow-codemod typeParameterBoundExactEmptyObjectToInexact.

$3


Converts implicitly inexact object type syntax {} to explicitly inexact {...}.

Run with yarn run flow-codemod convertImplicitInexactObjectTypes.

$3


Converts explicitly exact object type syntax {| |} to be just be { }. To be done after you turn on exact_by_default=true in your .flowconfig.

Run with yarn run flow-codemod removeExplicitlyExactObjectTypeSyntax.

$3


Removes annotations nested inside of destructuring (e.g. const [o: number] = foo;). These are not valid Flow syntax.

Run with yarn run flow-codemod removeAnnotationsInDestructuring.

Part of the upgrade to 0.176

$3

Removes useless duplicate class properties and fixes bad constructor binding in those classes.

Run with yarn run flow-codemod removeDuplicateClassProperties.

Part of the upgrade to 0.170

$3


Renames usages of the $Partial utility type to its new name, Partial.

Run with yarn run flow-codemod renamePartial.

Part of the upgrade to 0.201

$3


Converts usages of the deprecated and unsafe $Shape utility type to its replacement, Partial.

Run with yarn run flow-codemod convertShapeToPartial.

$3


Converts usages of the old casting syntax (x: T) to the new casting syntax x as T.

Run with yarn run flow-codemod typeCastToAsExpression.

$3


Converts usages of the internal React types like React$Node to public facing ones like React.Node.

Run with yarn run flow-codemod replaceReactDollarUtilityTypes.

$3


Converts:
- $TEMPORARY$object<{props}> to $ReadOnly<{props}>
- $TEMPORARY$array to $ReadOnlyArray
- $TEMPORARY$number<42> annotations to number
- $TEMPORARY$string<"foo"> annotations to string

$3

Converts:

- React.AbstractComponent to React.ComponentType
- React.ElementConfig> to Props
- React.ElementRef> to Instance
- React.ElementRef to mixed

$3


Converts legacy Flow utility types to TypeScript-compatible equivalents:
- $NonMaybeType to NonNullable
- $ReadOnly to Readonly
- $ReadOnlyArray to ReadonlyArray
- $ReadOnlyMap to ReadonlyMap
- $ReadOnlySet to ReadonlySet
- $Keys to keyof T
- $Values to Values
- mixed to unknown

Run with yarn run flow-codemod convertLegacyUtilityTypes`.