transform-flow-strip-types removes all jsdoc comments.

[ozum]

This is a bug report.

babel-plugin-transform-flow-strip-types removes all jsdoc comments, if source file contains only flowtype code and no regular javascript. When there is some regular javascript code i.e. const a = 1, jsdoc comments are preserved.

Input Code

// @flow
/**
 * Description of type
 * @typedef  {Object} SomeType
 * @property {string} name - name
 */
export type SomeType = {| name: string |};

Babel/Babylon Configuration (.babelrc, package.json, cli command)

{
  "presets": [
    "flow", ["env", { "targets": { "node": "current" }, "useBuiltIns": true }]
  ],
  "plugins": [
    "add-module-exports",
    "transform-export-extensions"
  ],
  "env": {
    "test": {
      "plugins": [
        ["istanbul", { "useInlineSourceMaps": false }]
      ]
    }
  }
}

Expected Behavior

"use strict";
//# sourceMappingURL=rule-config.js.map
/**
 * Description of type
 * @typedef  {Object} SomeType
 * @property {string} name - name
 */

Current Behavior

"use strict";
//# sourceMappingURL=rule-config.js.map

Possible Solution

Comments should be preserved, even there is no js code.

Context

I'm using flow for static type checking and jsdoc for documentation purposes. Since babel-plugin-transform-flow-strip-types removes all jsdoc comments, documentation affected negatively.

Your Environment

software	version(s)
Babel	6.26.0
Babylon
node	9.2.0
npm	5.5.1
Operating System	macOS 10.12.6

[babel-bot]

Hey @ozum! 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.

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[Arfey]

Are you sure that it's transform-flow-strip-types remove comments?
transform-flow-strip-types remove only comments that including @flow.

You can see test for your case:
actual
https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-flow-strip-types/test/fixtures/strip-types/strip-directive/actual.js
expected
https://github.com/babel/babel/blob/master/packages/babel-plugin-transform-flow-strip-types/test/fixtures/strip-types/strip-directive/expected.js

[nicolo-ribaudo]

It's because that comment is attatched to the tpe declaration node, which is removed.

[ozum]

@Arfey, I'm sure it's from transform-flow-strip-types, I tried by removing all other plugins.

@nicolo-ribaudo, yes it is a type declaration comment, but not a flow comment. As @Arfey said, only comments that includes @flow should be removed. Also if I add a single expression, comments are not deleted. Please see two examples below:

Without regular JS

// @flow
/**
 * Description of type
 * @typedef  {Object} SomeType
 * @property {string} name - name
 */
export type SomeType = {| name: string |};

is transpiled to

"use strict";
//# sourceMappingURL=fields.js.map

With regular JS

// @flow
/**
 * Description of type
 * @typedef  {Object} SomeType
 * @property {string} name - name
 */
export type SomeType = {| name: string |};
1;

is transpiled to:

"use strict";

1;

/**
 * Description of type
 * @typedef  {Object} SomeType
 * @property {string} name - name
 */
//# sourceMappingURL=fields.js.map

[loganfsmyth]

Hmm, this is a tough one. We probably can address this with special logic if we decide to, but no matter what you'll kind of be walking a fine line. We don't generally guarantee that comments will pass through as-is, for Babel transforms because our parsed representation isn't exact for comments.

[xtuc]

Closing, out of scope for now.