Global scope variables from within a function - Typescript

Question

I need to return a value from within a function and that function pdf.create().tofile() always returns undefined. Now if I explicitly try to return a variable by making it global, I am not able to do it in typescript. Can someone help? Please refer as below:

var serviceS3Result: any;
await pdf
  .create(stocksReport({}))
  .toFile(`./dist/test.pdf`, async (err, res) => {
    if (err) console.log(err);
    console.log('hi from inside', res);
    serviceS3Result = await this.s3Service.uploadFileFromSystem(
      `test`,
      fs.readFileSync(`./dist/test.pdf`),
      `test.pdf`
    );
    fs.unlinkSync(`./dist/test.pdf`);
  });
return serviceS3Result;

this returns undefined, any idea why?

which library is used for pdf? At least from the snippet, it looks like the operation toFile accepts callback... — Nalin Ranjan
– Nalin Ranjan, Commented May 3, 2022 at 6:52
@NalinRanjan Sorry I did not mention it, it is the 'html-pdf' - link no it does not accept a callback only the HTML and the format of the converted pdf as said in the document. and yes toFile() accepts a callback but that is always returning undefined. — Rajarshi Ghoshal
– Rajarshi Ghoshal, Commented May 3, 2022 at 6:57

AquaPI · Accepted Answer · 2022-05-03 11:07:57Z

2

the .toFile call does not return a Promise, so await is actually useless here.

So the solution here is to wrap the call into a Promise then resolve the value:

return new Promise((resolve, reject) => {
    pdf.create(stocksReport({}))
        .toFile(`./dist/test.pdf`, async (err, res) => {
            if (err) reject(err);
            console.log('hi from inside', res);
            // The promise fulfills here
            resolve(await this.s3Service.uploadFileFromSystem(
                `test`,
                 fs.readFileSync(`./dist/test.pdf`),
                 `test.pdf`
            ));
            fs.unlinkSync(`./dist/test.pdf`);
        });
});

edited May 3, 2022 at 11:07

answered May 3, 2022 at 7:08

AquaPI

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3 Comments

Taxel Over a year ago

Small mistake: instead of res(await ... it should be resolve(

Nalin Ranjan Over a year ago

Good that you addressed the err handling as well in inside the callback.

Rajarshi Ghoshal Over a year ago

@Taxel, KhanhBao.. Awesome! Thanks a lot! Learned something today.

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