Extract Font Name from PDF

I am using pdf.js to extract text from the pdf but the font name appears as g_d0_f6 etc. I need the font name to use the appropriate table for converting to Unicode. Here is the code derived from pdf2svg.js sample:-

var fs = require('fs');
var util = require('util');
var path = require('path');
var stream = require('stream');

// HACK few hacks to let PDF.js be loaded not as a module in global space.
require('./domstubs.js').setStubs(global);

var pdfjsLib = require('pdfjs-dist');

var pdfPath = process.argv[2] || '../../web/compressed.tracemonkey-pldi-09.pdf';
var data = new Uint8Array(fs.readFileSync(pdfPath));

var loadingTask = pdfjsLib.getDocument({
  data: data,
  nativeImageDecoderSupport: pdfjsLib.NativeImageDecoding.DISPLAY,
});
loadingTask.promise.then(function(doc) {
  var lastPromise = Promise.resolve(); // will be used to chain promises
  var loadPage = function (pageNum) {
    return doc.getPage(pageNum).then(function (page) {
      return page.getTextContent().then(function (textContent) {
    console.log(textContent);
        });
      });
    };

  for (var i = 1; i <= doc.numPages; i++) {
    lastPromise = lastPromise.then(loadPage.bind(null, i));
  }
  return lastPromise;
}).then(function () {
  console.log('# End of Document');
}, function (err) {
  console.error('Error: ' + err);
});

Sample output:-

{ items: 
   [ { str: 'bl fp=k osQ ckjs esa cPpksa ls ckrphr djsa & ;g LowQy esa fdl le; dk n`\'; gS\\ cPps',
       dir: 'ltr',
       width: 396.2250000000001,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 'D;k dj jgs gSa\\ cPps dkSu&dkSu ls [ksy] [ksy j',
       dir: 'ltr',
       width: 216.1650000000001,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 'g',
       dir: 'ltr',
       width: 6.42,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 's gSa\\ fp=k esa fdrus cPps gSa vkSj fdrus',
       dir: 'ltr',
       width: 173.865,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 'cM+s gSa\\ vkil esa dkSu D;k ckr dj jgk gksxk\\ cPpksa ls fp=k esa lcosQ fy, uke lkspus',
       dir: 'ltr',
       width: 396.54000000000013,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 'dks dgasaA',
       dir: 'ltr',
       width: 40.74,
       height: 15,
       transform: [Array],
       fontName: 'g_d0_f1' },
     { str: 'csVh cpkvks',
       dir: 'ltr',
       width: 66.725,
       height: 17,
       transform: [Array],
       fontName: 'g_d0_f2' },
     { str: 'csVh i<+kvksA',
       dir: 'ltr',
       width: 66.75899999999999,
       height: 17,
       transform: [Array],
       fontName: 'g_d0_f2' },
     { str: '2018-19',
       dir: 'ltr',
       width: 36.690000000000005,
       height: 10,
       transform: [Array],
       fontName: 'g_d0_f3' } ],
  styles: 
   { g_d0_f1: 
      { fontFamily: 'sans-serif',
        ascent: 0.837,
        descent: -0.216,
        vertical: false },
     g_d0_f2: 
      { fontFamily: 'sans-serif',
        ascent: 0.786,
        descent: -0.181,
        vertical: false },
     g_d0_f3: 
      { fontFamily: 'sans-serif',
        ascent: 0.9052734375,
        descent: -0.2119140625,
        vertical: false } } }

And here is the pdf that uses embedded fonts: http://ncert.nic.in/textbook/pdf/ahhn101.pdf

Here is a related question but the suggested commonObjs is empty: pdf.js get info about embedded fonts

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