README
pdfreader 
Read text and parse tables from PDF files.
Supports tabular data with automatic column detection, and rule-based parsing.
Dependencies: it is based on pdf2json, which itself relies on Mozilla's pdf.js.
ℹ️ This module is meant to be run using Node.js only. It does not work from a web browser.
Summary:
- Installation, tests and CLI usage
- Raw PDF reading (incl. examples)
- Rule-based data extraction
- Troubleshooting & FAQ
Installation, tests and CLI usage (make sure node v8 or v10)
npm install pdfreader
cd node_modules/pdfreader
npm test
node parse.js test/sample.pdf
Raw PDF reading
This module exposes the PdfReader class, to be instantiated.
Your instance has two methods for parsing a PDF. They return the same output and differ only in input: PdfReader.parseFileItems (as below) for a filename, and PdfReader.parseBuffer (see: "Raw PDF reading from a PDF already in memory (buffer)") from data that you don't want to reference from the filesystem.
Whichever method you choose, it asks for a callback, which gets called each time the instance finds what it denotes as a PDF item.
An item object can match one of the following objects:
null, when the parsing is over, or an error occured.- File metadata,
{file:{path:string}}, when a PDF file is being opened, and is always the first item. - Page metadata,
{page:integer, width:float, height:float}, when a new page is being parsed, provides the page number, starting at 1. This basically acts as a carriage return for the coordinates of text items to be processed. - Text items,
{text:string, x:float, y:float, w:float, ...}, which you can think of as simple objects with a text property, and floating 2D AABB coordinates on the page.
It's up to your callback to process these items into a data structure of your choice, and also to handle any errors thrown to it.
For example:
new PdfReader().parseFileItems("sample.pdf", function (err, item) {
if (err) callback(err);
else if (!item) callback();
else if (item.text) console.log(item.text);
});
Raw PDF reading from a PDF already in memory (buffer)
As above, but reading from a buffer in memory rather than from a file referenced by path. For example:
var fs = require("fs");
fs.readFile("sample.pdf", (err, pdfBuffer) => {
// pdfBuffer contains the file content
new PdfReader().parseBuffer(pdfBuffer, function (err, item) {
if (err) callback(err);
else if (!item) callback();
else if (item.text) console.log(item.text);
});
});
Example: reading from a buffer of an online PDF
const https = require("https");
const pdfreader = require("pdfreader");
async function bufferize(url) {
var hn = url.substring(url.search("//") + 2);
hn = hn.substring(0, hn.search("/"));
var pt = url.substring(url.search("//") + 2);
pt = pt.substring(pt.search("/"));
const options = { hostname: hn, port: 443, path: pt, method: "GET" };
return new Promise(function (resolve, reject) {
var buff = new Buffer.alloc(0);
const req = https.request(options, (res) => {
res.on("data", (d) => {
buff = Buffer.concat([buff, d]);
});
res.on("end", () => {
resolve(buff);
});
});
req.on("error", (e) => {
console.error("https request error: " + e);
});
req.end();
});
}
/*
if second param is set then a space ' ' inserted whenever text
chunks are separated by more than xwidth
this helps in situations where words appear separated but
this is because of x coords (there are no spaces between words)
each page is a different array element
*/
async function readlines(buffer, xwidth) {
return new Promise((resolve, reject) => {
var pdftxt = new Array();
var pg = 0;
new pdfreader.PdfReader().parseBuffer(buffer, function (err, item) {
if (err) console.log("pdf reader error: " + err);
else if (!item) {
pdftxt.forEach(function (a, idx) {
pdftxt[idx].forEach(function (v, i) {
pdftxt[idx][i].splice(1, 2);
});
});
resolve(pdftxt);
} else if (item && item.page) {
pg = item.page - 1;
pdftxt[pg] = [];
} else if (item.text) {
var t = 0;
var sp = "";
pdftxt[pg].forEach(function (val, idx) {
if (val[1] == item.y) {
if (xwidth && item.x - val[2] > xwidth) {
sp += " ";
} else {
sp = "";
}
pdftxt[pg][idx][0] += sp + item.text;
t = 1;
}
});
if (t == 0) {
pdftxt[pg].push([item.text, item.y, item.x]);
}
}
});
});
}
(async () => {
var url =
"https://www.w3.org/TR/2011/NOTE-WCAG20-TECHS-20111213/working-examples/PDF2/bookmarks.pdf";
var buffer = await bufferize(url);
var lines = await readlines(buffer);
lines = await JSON.parse(JSON.stringify(lines));
console.log(lines);
})();
Example: parsing lines of text from a PDF file
Here is the code required to convert this PDF file into text:
var pdfreader = require("pdfreader");
var rows = {}; // indexed by y-position
function printRows() {
Object.keys(rows) // => array of y-positions (type: float)
.sort((y1, y2) => parseFloat(y1) - parseFloat(y2)) // sort float positions
.forEach((y) => console.log((rows[y] || []).join("")));
}
new pdfreader.PdfReader().parseFileItems(
"CV_ErhanYasar.pdf",
function (err, item) {
if (!item || item.page) {
// end of file, or page
printRows();
console.log("PAGE:", item.page);
rows = {}; // clear rows for next page
} else if (item.text) {
// accumulate text items into rows object, per line
(rows[item.y] = rows[item.y] || []).push(item.text);
}
}
);
Fork this example from parsing a CV/résumé.
Example: parsing a table from a PDF file
Here is the code required to convert this PDF file into a textual table:
var pdfreader = require("pdfreader");
const nbCols = 2;
const cellPadding = 40; // each cell is padded to fit 40 characters
const columnQuantitizer = (item) => parseFloat(item.x) >= 20;
const padColumns = (array, nb) =>
Array.apply(null, { length: nb }).map((val, i) => array[i] || []);
// .. because map() skips undefined elements
const mergeCells = (cells) =>
(cells || [])
.map((cell) => cell.text)
.join("") // merge cells
.substr(0, cellPadding)
.padEnd(cellPadding, " "); // padding
const renderMatrix = (matrix) =>
(matrix || [])
.map((row, y) => padColumns(row, nbCols).map(mergeCells).join(" | "))
.join("\n");
var table = new pdfreader.TableParser();
new pdfreader.PdfReader().parseFileItems(filename, function (err, item) {
if (!item || item.page) {
// end of file, or page
console.log(renderMatrix(table.getMatrix()));
console.log("PAGE:", item.page);
table = new pdfreader.TableParser(); // new/clear table for next page
} else if (item.text) {
// accumulate text items into rows object, per line
table.processItem(item, columnQuantitizer(item));
}
});
Fork this example from parsing a CV/résumé.
Example: opening a PDF file with a password
new PdfReader({ password: "YOUR_PASSWORD" }).parseFileItems(
"sample-with-password.pdf",
function (err, item) {
if (err) callback(err);
else if (!item) callback();
else if (item.text) console.log(item.text);
}
);
Rule-based data extraction
The Rule class can be used to define and process data extraction rules, while parsing a PDF document.
Rule instances expose "accumulators": methods that defines the data extraction strategy to be used for each rule.
Example:
var processItem = Rule.makeItemProcessor([
Rule.on(/^Hello \"(.*)\"$/)
.extractRegexpValues()
.then(displayValue),
Rule.on(/^Value\:/)
.parseNextItemValue()
.then(displayValue),
Rule.on(/^c1$/).parseTable(3).then(displayTable),
Rule.on(/^Values\:/)
.accumulateAfterHeading()
.then(displayValue),
]);
new PdfReader().parseFileItems("sample.pdf", function (err, item) {
processItem(item);
});
Troubleshooting & FAQ
Is it possible to parse a PDF document from a web application?
Solutions exist, but this module cannot be run directly by a web browser. If you really want to use this module, you will have to integrate it into your back-end so that PDF files can be read from your server.
Cannot read property 'userAgent' of undefined error from an express-based node.js app
Dmitry found out that you may need to run these instructions before including the pdfreader module:
global.navigator = {
userAgent: "node",
};
window.navigator = {
userAgent: "node",
};