converting json to pdf file and download file using react / javascript

I want to convert json data into a pdf file. Can you please point me in a helpful direction?
For example, I'd like to convert this json;

NOTE: I want to do it without using any library.

{"employees":[
    {"firstName":"John", "lastName":"Doe"}, 
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"Peter", "lastName":"Jones"}
]}

Employees

FirstName: John  LastName  :Doe

FirstName: Anna LastName  :Smith

FirstName: Peter LastName  :Jones

I want to create pdf first and then download the pdf file I created.

I try:

fetch('https://catfact.ninja/fact/', {
      method: 'GET',
      headers: {
        'Content-Type': 'application/pdf',
      },
    })
      .then((response) => response.blob())
      .then((blob) => {
        // Create blob link to download
        const url = window.URL.createObjectURL(
          new Blob([blob]),
        );
        const link = document.createElement('a');
        link.href = url;
        link.setAttribute(
          'download',
          `FileName.pdf`,
        );

        // Append to html link element page
        document.body.appendChild(link);

        // Start download
        link.click();

        // Clean up and remove the link
        link.parentNode.removeChild(link);
      });

but this document does not work.

NOTE: I want to do it without using any library.

In order to convert json into PDF without any dependency than text string edits, you need to restructure the text as a PDF something like this

%PDF-1.1
%âãÏÓ
1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj
2 0 obj<</Type/Pages/Kids [3 0 R]/Count 1/MediaBox [0 0 594 792]>>endobj
3 0 obj<</Type/Page/Parent 2 0 R/Resources<</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Helvetica>>>>>>/Contents 4 0 R>>endobj
4 0 obj<</Length 302
>>
stream

BT /F1 18 Tf 036 740 Td (Employees) Tj ET
BT /F1 16 Tf 036 720 Td (FirstName: John) Tj ET
BT /F1 16 Tf 236 720 Td (LastName: Doe) Tj ET
BT /F1 16 Tf 036 700 Td (FirstName: Anna) Tj ET
BT /F1 16 Tf 236 700 Td (LastName: Smith) Tj ET
BT /F1 16 Tf 036 680 Td (FirstName: Peter) Tj ET
BT /F1 16 Tf 236 680 Td (LastName: Jones) Tj ET
BT /F1 16 Tf 036 660 Td (FirstName: ) Tj ET
BT /F1 16 Tf 236 660 Td (LastName: ) Tj ET

endstream 
endobj
xref
0 5 
0000000000 65535 f
0000000021 00000 n
0000000065 00000 n
0000000139 00000 n
0000000269 00000 n
trailer<</Root 1 0 R /Size 5>>
startxref
752
%%EOF

the hard part is how to count and decide on /Length 302 and 752 get them wrong and the file is likely rejected or complains of a fault.