Function createSwcOptions

src/transpilers/swc.ts:126–270

(
  compilerOptions: ts.CompilerOptions,
  nodeModuleEmitKind: NodeModuleEmitKind | undefined,
  swcInstance: SwcInstance,
  swcDepName: string
)

 * @internal exported for testing
 */
export function createSwcOptions(
  compilerOptions: ts.CompilerOptions,
  nodeModuleEmitKind: NodeModuleEmitKind | undefined,
  swcInstance: SwcInstance,
  swcDepName: string
) {
  const {
    esModuleInterop,
    sourceMap,
    importHelpers,
    experimentalDecorators,
    emitDecoratorMetadata,
    target,
    module,
    jsx,
    jsxFactory,
    jsxFragmentFactory,
    strict,
    alwaysStrict,
    noImplicitUseStrict,
    jsxImportSource,
  } = compilerOptions;

  let swcTarget = targetMapping.get(target!) ?? 'es3';
  // Downgrade to lower target if swc does not support the selected target.
  // Perhaps project has an older version of swc.
  // TODO cache the results of this; slightly faster
  let swcTargetIndex = swcTargets.indexOf(swcTarget);
  for (; swcTargetIndex >= 0; swcTargetIndex--) {
    try {
      swcInstance.transformSync('', {
        jsc: { target: swcTargets[swcTargetIndex] as swcWasm.JscTarget },
      });
      break;
    } catch (e) {}
  }
  swcTarget = swcTargets[swcTargetIndex];
  const keepClassNames = target! >= /* ts.ScriptTarget.ES2016 */ 3;
  const isNodeModuleKind = module === ModuleKind.Node16 || module === ModuleKind.NodeNext;
  // swc only supports these 4x module options [MUST_UPDATE_FOR_NEW_MODULEKIND]
  const moduleType =
    module === ModuleKind.CommonJS
      ? 'commonjs'
      : module === ModuleKind.AMD
      ? 'amd'
      : module === ModuleKind.UMD
      ? 'umd'
      : isNodeModuleKind && nodeModuleEmitKind === 'nodecjs'
      ? 'commonjs'
      : isNodeModuleKind && nodeModuleEmitKind === 'nodeesm'
      ? 'es6'
      : 'es6';
  // In swc:
  //   strictMode means `"use strict"` is *always* emitted for non-ES module, *never* for ES module where it is assumed it can be omitted.
  //   (this assumption is invalid, but that's the way swc behaves)
  // tsc is a bit more complex:
  //   alwaysStrict will force emitting it always unless `import`/`export` syntax is emitted which implies it per the JS spec.
  //   if not alwaysStrict, will emit implicitly whenever module target is non-ES *and* transformed module syntax is emitted.