Attempt to reduce Core bundle size with type exports. #92221
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mshustov
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v8.0.0
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| @@ -9,4 +9,5 @@ | |||
| import { CspConfig, ICspConfig } from './csp_config'; | |||
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question: out of curiosity, is there any benefits in doing import + export comparing to only using export's like this or is it just a matter of personal taste?
export type { ICspConfig } from './csp_config';
export type { CspConfigType } from './config';
export { config } from './config';
export { CspConfig } from './csp_config';There was a problem hiding this comment.
out of curiosity, is there any benefits in doing import + export comparing to only using export's like this or is it just a matter of personal taste?
I don't think it provides extra benefits. The compiler already knows how the imported code is used in the file. So it can remove all the imports used as interfaces or types.
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* compile core files as isolated modules * fix export problems for isolated modules * apply changes to kbn-test as core imports from it * fix some exports * fix lint errors * update new exports * fix eslint error * expand export * where it is possible * update docs * update docs * fix eslint error # Conflicts: # api_docs/core.json # api_docs/core_application.json # api_docs/core_http.json # api_docs/core_saved_objects.json # src/core/public/index.ts
Summary
Closes #58113
When a developer exports something from a module that can be at the same time runtime code (for example, a
Class) and a type, Babel doesn't remove such export.It can affect the
Page load bundlesize, since often we want to provide a type to 3rd party modules, but not an implementation.In this PR I leverage isolatedModules flag for
tsccompiler that runs compilation for every file independently. To make it possible,tscenforces all the types to be re-exported asexport type { ... }. This, in turn, requires developers to evaluate every re-export to decide how it should be exported.The algorithm is simple:
export type {... }export { ... }By default, always export classes as
export typeif you don't want users to rely on a concrete implementation.This heuristic with manual
export typedeclaration helps our build chain to strip unnecessary runtime exports.In this PR, it shaved off about 10% of the page load bundle size of Core.
I already leveraged this approach once in #79635, which saved us ~220 KB there.