pdf-parse VS polyfill

pdf-parse is a popular parsing package among developers for its user-friendly interface. Its stability stems from its independence from other parser frameworks, which contributes to fewer bugs.

The first issue we faced was getting the text contents from a PDF file. While extracting text directly from PDF, using open source tools like pdf-parse (which is used internally by langchain’s pdf-loader) did the job most of the time, we still had some issues with it: some PDFs were not parsed correctly and the tool returned empty string (like in the case of Uber sample pitchdeck ), we’ve just got some words split into individual characters and so on.

import { PdfReader, TableParser } from "pdfreader"; const filename = "./uploads/table.pdf"; const nbCols = 2; const cellPadding = 40; const columnQuantitizer = (item) => parseFloat(item.x) >= 20; // polyfill for String.prototype.padEnd() // https://github.com/uxitten/polyfill/blob/master/string.polyfill.js // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/repeat if (!String.prototype.padEnd) { String.prototype.padEnd = function padEnd(targetLength, padString) { targetLength = targetLength >> 0; //floor if number or convert non-number to 0; padString = String(padString || " "); if (this.length > targetLength) { return String(this); } else { targetLength = targetLength - this.length; if (targetLength > padString.length) { padString += padString.repeat(targetLength / padString.length); //append to original to ensure we are longer than needed } return String(this) + padString.slice(0, targetLength); } }; } const padColumns = (array, nb) => Array.apply(null, { length: nb }).map((val, i) => array[i] || []); const mergeCells = (cells) => (cells || []).map((cell) => cell.text).join(""); const formatMergedCell = (mergedCell) => mergedCell.substr(0, cellPadding).padEnd(cellPadding, " "); const renderMatrix = (matrix) => (matrix || []) .map( (row, y) => "| " + padColumns(row, nbCols) .map(mergeCells) .map(formatMergedCell) .join(" | ") + " |" ) .join("\n"); var table = new TableParser(); new PdfReader().parseFileItems(filename, function (err, item) { if (err) console.error(err); else if (!item || item.page) { // end of file, or page console.log(renderMatrix(table.getMatrix())); item?.page && console.log("PAGE:", item.page); table = new TableParser(); // new/clear table for next page } else if (item.text) { // accumulate text items into rows object, per line table.processItem(item, columnQuantitizer(item)); } });