transformES5.ts

    const options = {
      ...this.compilerOptions,
      target: ts.ScriptTarget.ES5,
    };
    // @ts-expect-error foo
    const scriptTransformers = ts.getTransformers(options).scriptTransformers;

    const transformer: ts.TransformerFactory<ts.SourceFile> = (context) => {
      return (sourceFile) => {
        const visitor = (node: ts.Node): ts.Node => {
          if (ts.isParameter(node)) {
            return context.factory.updateParameterDeclaration(
              node,
              node.modifiers,
              node.dotDotDotToken,
              'foo',
              node.questionToken,
              node.type,
              node.initializer,
            );
          }

          return ts.visitEachChild(node, visitor, context);
        };

        return ts.visitNode(sourceFile, visitor) as ts.SourceFile;
      };
    };
    const customTransformers = scriptTransformers.slice(3, 11);

    const { transformed } = ts.transform(this.sourceFile, customTransformers);

    const printer = ts.createPrinter();
    const str = printer.printNode(
      ts.EmitHint.SourceFile,
      transformed[0],
      transformed[0],
    );
    console.log(str);