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perf: skip unused transform options in strip-only mode #484

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Merged
marco-ippolito merged 2 commits into from
Oct 19, 2026
Merged

perf: skip unused transform options in strip-only mode #484

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d1dd0e7
perf: skip unused transform options in strip-only mode
GroophyLifefor Oct 17, 2026
1903054
refactor: use separate default options per mode
GroophyLifefor Oct 18, 2026
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17 changes: 11 additions & 6 deletions src/internal.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,25 +8,30 @@ import swc from "../lib/wasm.js";
const DEFAULT_OPTIONS = {
mode: "strip-only",
deprecatedTsModuleAsError: true,
// default transform will only work when mode is "transform"
} satisfies Options;

// swc only reads `transform` in "transform" mode, so these defaults are kept
// out of strip-only calls to avoid deserializing them on every call.
const DEFAULT_TRANSFORM_OPTIONS = {
mode: "transform",
deprecatedTsModuleAsError: true,
transform: {
verbatimModuleSyntax: true,
nativeClassProperties: true,
noEmptyExport: true,
importNotUsedAsValues: "preserve",
},
} as Options;
} satisfies Options;

export function transformSync(
source: string,
options?: Options,
): TransformOutput {
// Ensure that the source code is a string
const input = `${source ?? ""}`;
return swc.transformSync(input, {
...DEFAULT_OPTIONS,
...options,
});
const defaults =
options?.mode === "transform" ? DEFAULT_TRANSFORM_OPTIONS : DEFAULT_OPTIONS;
return swc.transformSync(input, { ...defaults, ...options });
}

export function transformModuleSyntax(
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