Babel: @babel/standalone transform cannot set presets stage-0

[songyule]

Bug Report

• [ ] I would like to work on a fix!

Current Behavior
when i use Babel.transform(version: @babel/[email protected]) set presets stage-0, i got an error
Error: [BABEL] unknown: The decorators plugin requires a 'decoratorsBeforeExport' option, whose value must be a boolean. If you want to use the legacy decorators semantics, you can set the 'legacy: true' option. (While processing: "base$1$0$0$0")
But I use the old version(@babel/[email protected]) and the same behavior works
Input Code

• REPL or Repo link if applicable:
  https://codesandbox.io/s/amazing-moon-6glcz

import * as Babel from "@babel/standalone";
  const testCode = `
    class App extends React.Component {
      state = { value: '' }
      onChange = e => {
        this.setState({value: e.target.value});
      }
      render() {
        return (
          <label>
            Enter a value111111:
            <br />
            <input type="text" value={this.state.value} onChange={this.onChange} />
          </label>
        )
      }
    }  
  `;
    const outputCode = Babel.transform(testCode, {
      presets: ["react", "stage-0"],
      plugins: [
        "proposal-class-properties",
        ["proposal-decorators", { legacy: true }]
      ]
    }).code;

Expected behavior/code
A clear and concise description of what you expected to happen (or code).

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

• Filename: babel.config.js

Environment

@babel/standalone version: v7.8.6
Node/npm version: v10.16.0/v6.9.0
OS: macOS v10.15.1

Possible Solution

Additional context/Screenshots
Add any other context about the problem here. If applicable, add screenshots to help explain.

[babel-bot]

Hey @songyule! 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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[JLHwung]

We should add default value true for decoratorsBeforeExport options accepted in the following places:

https://github.com/babel/babel/blob/21c91418722e3b0c0e9042427bb1524baebba452/packages/babel-standalone/src/preset-stage-0.js#L10

and preset-stage-1.js, preset-stage-2.js.

PR is welcome!

See Nicolò's comment below.

[nicolo-ribaudo]

We didn't add a default value on purpose: it wasn't clear which one we should have used. The current proposal has decorators _after_ export, but it's a completely different proposal from the one implemented in Babel.

This is a configuration error: in that sandbox, both "modern" and "legacy" decorators are enabled. "modern" decorators using the stage-0 preset, and "legacy" using the plugin.

This should work:

    const outputCode = Babel.transform(testCode, {
      presets: [
        "react",
        ["stage-0", { decoratorsLegacy: true }]
       ]
    }).code;

[songyule]

We didn't add a default value on purpose: it wasn't clear which one we should have used. The current proposal has decorators _after_ export, but it's a completely different proposal from the one implemented in Babel.

This is a configuration error: in that sandbox, both "modern" and "legacy" decorators are enabled. "modern" decorators using the stage-0 preset, and "legacy" using the plugin.

This should work:

    const outputCode = Babel.transform(testCode, {
      presets: [
        "react",
        ["stage-0", { decoratorsLegacy: true }]
       ]
    }).code;

thx, It's ready to work