Customize @vitejs/plugin-legacy babel options

[IlyaSemenov]

Description

As a developer using Vite I want to have more control on what options @vitejs/plugin-legacy passes to babel. Currently, the only option that I can control is targets:

vite/packages/plugin-legacy/src/index.ts

Lines 440 to 446 in 447df7c

	[
	'@babel/preset-env',
	createBabelPresetEnvOptions(targets, {
	needPolyfills,
	ignoreBrowserslistConfig: options.ignoreBrowserslistConfig,
	}),
	],

I would like to be able to at least pass include to inject additional babel plugins.

Suggested solution

Whatever. It could be an object to be merged with the result of createBabelPresetEnvOptions, or a callback that modifies the options coming from createBabelPresetEnvOptions before they are passed to babel.

Alternative

No response

Additional context

The actual problem I am trying to solve is #13038: the "chrome 49" legacy target yields broken code due to missing additional babel transformations (see here).

Even though this could be an upstream problem in @babel/preset-env, if this kind of customization was possible I would be able to come up with a workaround on Vite level.

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[sapphi-red]

Closing as the actual problem is seems to be already fixed. If other users have a concrete use case for this, feel free to create a new issue.