printer.printFile function is generating a blank output

Utilizing the compiler API for Typescript code generation, I encountered an issue where printer.printFile consistently outputs empty strings. Despite successfully using printer.printNode and printer.printList to print my AST, printer.printFile remains uncooperative.

const printer = createPrinter();
    
const sourceFile = createSourceFile(
  'dummy.ts',
  '',
  ScriptTarget.ESNext,
  false,
  ScriptKind.TS
);

const classDeclaration = factory.createClassDeclaration(
  undefined,
  undefined,
  'Foo',
  undefined,
  undefined,
  []
);

factory.updateSourceFile(sourceFile, factory.createNodeArray([classDeclaration]));

console.log(printer.printFile(sourceFile)); // '';

I am perplexed by the behavior of printer.printFile and would appreciate any insights on why it consistently results in an empty string.

typescript

Answer №1

It's interesting to note that the function factory.updateSourceFile seems to return the modified SourceFile.

const printer = createPrinter();
   
// convert const to let
let sourceFile = createSourceFile(
  'dummy.ts',
  '',
  ScriptTarget.ESNext,
  false,
  ScriptKind.TS
);

const classDeclaration = factory.createClassDeclaration(
  undefined,
  undefined,
  'Foo',
  undefined,
  undefined,
  []
);

// update the source file with the new class declaration
sourceFile = factory.updateSourceFile(sourceFile, factory.createNodeArray([classDeclaration]));

console.log(printer.printFile(sourceFile));
// class Foo {
// }

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