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Typesafe babel plugin development with TypeScript #10637

hbroer opened this issue Nov 4, 2019 · 2 comments


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@hbroer hbroer commented Nov 4, 2019

Feature Request

Is your feature request related to a problem? Please describe.
I miss some types for plugin development in typescript which I need. I asked for some help at the slack channel but got no answer.

  1. I can't find the type for PluginPass ( It should be exported to make it usable like in this example:
import * as types from "@babel/types";
import {ImportDeclaration} from "@babel/types";
import {NodePath, PluginPass} from "@babel/traverse";
// or import {NodePath, PluginPass} from "@babel/core";

export default function({ types: t }: {types: typeof types}) {
    return {
        name: "example plugin",
        visitor: {
            ImportDeclaration(path: NodePath<ImportDeclaration>, pass: PluginPass) {}
  1. The plugin function has no return type but it should to display errors and to make code completion possible, like this:
import {PluginDefinition} from "@babel/core";

export default function(): PluginDefinition {
    return {}; // this should be a TS error because `name` is missing
  1. {types: typeof types} is strange also would be this: typeof babel. This is a workaround which describes the plugin default function parameter. This should also a dedicated type:
import {PluginDefinition, Babel} from "@babel/core";

export default function({ types: t }: Babel): PluginDefinition {}

Describe the solution you'd like
Export/add the types which are missing.

Describe alternatives you've considered
None. Declare everything as any is not a solution :-)

Teachability, Documentation, Adoption, Migration Strategy
The documentation/handbook should contain a example how to write plugins in TypeScript.


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@babel-bot babel-bot commented Nov 4, 2019

Hey @hbroer! We really appreciate you taking the time to report an issue. The collaborators on this project attempt to help as many people as possible, but we're a limited number of volunteers, so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack community that typically always has someone willing to help. You can sign-up here for an invite."


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@hbroer hbroer commented Nov 6, 2019

Just noticed that only 50% of the available Types come from @babel, the other 50% come from @types. :/

Also noticed one of the types I missed I just overead: PluginObj is the type of the function return value. But still missing the PluginPass definition.

And now I don't know who to ask, or where to add, the missing type...

export default function({types: t}: typeof babel): PluginObj {
    return {
        name: "example",
        visitor: {
            ImportDeclaration(path: NodePath<ImportDeclaration>, pass: any /*PluginPass*/) {}
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