Pdf reader in javascript

pdfreader

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.

• This module is meant to be run using Node.js only. It does not work from a web browser.
• This module extracts text entries from PDF files. It does not support photographed text. If you cannot select text from the PDF file, you may need to use OCR software first.

Installation, tests and CLI usage

nvm use # optional, to switch to the recommended version of Node.js 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. You can pass < debug: true >to the constructor, in order to log debugging information. (useful for troubleshooting)

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, > , when a PDF file is being opened, and is always the first item.
• Page metadata, , 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, , 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.

import  PdfReader > from "pdfreader"; new PdfReader().parseFileItems("test/sample.pdf", (err, item) =>  if (err) console.error("error:", err); else if (!item) console.warn("end of file"); else if (item.text) console.log(item.text); >);

Parsing a password-protected PDF file

new PdfReader( password: "YOUR_PASSWORD" >).parseFileItems( "test/sample-with-password.pdf", function (err, item)  if (err) console.error(err); else if (!item) console.warn("end of file"); else if (item.text) console.log(item.text); > );

Raw PDF reading from a PDF buffer

As above, but reading from a buffer in memory rather than from a file referenced by path. For example:

import fs from "fs"; import  PdfReader > from "pdfreader"; fs.readFile("test/sample.pdf", (err, pdfBuffer) =>  // pdfBuffer contains the file content new PdfReader().parseBuffer(pdfBuffer, (err, item) =>  if (err) console.error("error:", err); else if (!item) console.warn("end of buffer"); else if (item.text) console.log(item.text); >); >);

Other examples of use

Source code of the examples above: parsing a CV/résumé.

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.

const 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("test/sample.pdf", (err, item) =>  if (err) console.error(err); else 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", >;

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mozilla/pdf.js

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README.md

PDF.js is a Portable Document Format (PDF) viewer that is built with HTML5.

PDF.js is community-driven and supported by Mozilla. Our goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs.

PDF.js is an open source project and always looking for more contributors. To get involved, visit:

Feel free to stop by our Matrix room for questions or guidance.

Please note that the «Modern browsers» version assumes native support for the latest JavaScript features; please also see this wiki page.

PDF.js is built into version 19+ of Firefox.

• The official extension for Chrome can be installed from the Chrome Web Store. This extension is maintained by @Rob—W.
• Build Your Own — Get the code as explained below and issue gulp chromium . Then open Chrome, go to Tools > Extension and load the (unpackaged) extension from the directory build/chromium .

To get a local copy of the current code, clone it using git:

$ git clone https://github.com/mozilla/pdf.js.git $ cd pdf.js 

Next, install Node.js via the official package or via nvm. You need to install the gulp package globally (see also gulp’s getting started):

If everything worked out, install all dependencies for PDF.js:

Finally, you need to start a local web server as some browsers do not allow opening PDF files using a file:// URL. Run:

Please keep in mind that this assumes the latest version of Mozilla Firefox; refer to Building PDF.js for non-development usage of the PDF.js library.

It is also possible to view all test PDF files on the right side by opening:

In order to bundle all src/ files into two production scripts and build the generic viewer, run:

If you need to support older browsers, run:

This will generate pdf.js and pdf.worker.js in the build/generic/build/ directory (respectively build/generic-legacy/build/ ). Both scripts are needed but only pdf.js needs to be included since pdf.worker.js will be loaded by pdf.js . The PDF.js files are large and should be minified for production.

Using PDF.js in a web application

To use PDF.js in a web application you can choose to use a pre-built version of the library or to build it from source. We supply pre-built versions for usage with NPM and Bower under the pdfjs-dist name. For more information and examples please refer to the wiki page on this subject.

PDF.js is hosted on several free CDNs:

You can play with the PDF.js API directly from your browser using the live demos below:

More examples can be found in the examples folder. Some of them are using the pdfjs-dist package, which can be built and installed in this repo directory via gulp dist-install command.

For an introduction to the PDF.js code, check out the presentation by our contributor Julian Viereck:

More learning resources can be found at:

The API documentation can be found at:

Check out our FAQs and get answers to common questions:

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How to create a PDF Viewer in JavaScript

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PDF.js is a JavaScript library maintained by Mozilla and designed for handling PDFs in JavaScript.

We are going to create a PDF viewer that has the following functionalities:

• View a PDF
• Go to the next page
• Go to the previous page
• Go to a particular page number

Steps

Create an index.html file that includes:

• canvas → Where the pdf will be rendered.
• previous button → To go to the previous page.
• next button → To go to the next page.
• input box → To enter a page number.
• Go to page button → Button to go to a particular page.
• 2-span elements → Display the current page number and total pages of the PDF.

Initializing the JavaScript file for rendering the PDF

In addition to the index.html file, we will create a script.js file where we can write our JavaScript code to create a PDF viewer.

Initialize the variables

let pdf ; // to store pdf data let canvas; // to render pdf let isPageRendering; // to check if the pdf is currently rendering let pageRenderingQueue = null; // to store next page number to render let canvasContext; // context of canvas let totalPages; // total pages of pdf let currentPageNum = 1; 

Next, add event listeners to handle the PDF renderer once the page loads:

window.addEventListener('load', function () < isPageRendering= false; pageRenderingQueue = null; canvas = document.getElementById('pdf_canvas'); canvasContext = canvas.getContext('2d'); initEvents(); Add events initPDFRenderer(); // render first page >); 

Implement initPDFRenderer function

• We need to initialize the PDF.js with a source PDF
• We can use the getDocument method to get a promise that resolves to pdfData
• The PDF data has a getPage function
• The getPage will return a promise
• Once the promise is resolved , we get the page data
• We can then use the render method in the page data to render it in the canvas

function initPDFRenderer() < let url = 'https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/web/compressed.tracemonkey-pldi-09.pdf'; // const url = 'filepath.pdf'; // to load pdf from our machine let option = < url>; pdfjsLib.getDocument(option) .promise .then( pdfData => < totalPages = pdfData.numPages; // total number of pages let pagesCounter= document.getElementById('total_page_num'); // update total pages text pagesCounter.textContent = totalPages; // assigning read pdfContent to global variable pdf = pdfData; console.log(pdfData); renderPage(currentPageNum); >); > 

Now, when we call initPdfRenderer it will assign the pdfData to the PDF variable.

Add events for pagination buttons

Add events for previousButton , nextButton , and goToPage buttons.

Implement renderPage function

Now, let’s create a renderPage function to render the PDF page to the canvas.

function renderPage(pageNumToRender = 1) < isPageRendering = true; document.getElementById('current_page_num').textContent = pageNumToRender; // use getPage method pdf .getPage(pageNumToRender) .then( page =>< const viewport = page.getViewport(); canvas.height = viewport.height; canvas.width = viewport.width; let renderCtx = ; page .render(renderCtx) .promise .then(()=> < isPageRendering = false; // this is to check if there is next page to be rendered in the queue if(pageRenderingQueue !== null) < renderPage(pageRenderingQueue); pageRenderingQueue = null; >>); >); > 

We have a method to get pdfData and render the page. Let’s write our pageRenderingQueue .

If the user clicks next page/previous page, it will add/subtract 1 to the currentPageNum and pass it to the renderPageQueue method. This will check if the pageRenderingQueue is null. If it is null, then we call the renderPage method, or else it will assign the page number that is to be rendered to the queue . Once the page rendering is complete, it will check if the pageQueue is empty and perform the respective action (if needed).

function renderPageQueue(pageNum) < if(pageRenderingQueue != null) < pageRenderingQueue = pageNum; >else < renderPage(pageNum); >> 

Let’s create a renderNextPage and renderPreviousPage method. If the user clicks:

• next page – currentPageNum + 1 and render page.
• previous page – currentPageNum — 1 and render page.

function renderNextPage(ev) < if(currentPageNum >= totalPages) < alert("This is the last page"); return ; >currentPageNum++; renderPageQueue(currentPageNum); > function renderPreviousPage(ev) < if(currentPageNum<=1) < alert("This is the first page"); return ; >currentPageNum--; renderPageQueue(currentPageNum); > 

Now, let’s implement the “go to page number” function.

Get the page number from the input box, then check if the number is valid and call the renderPage method.

function goToPageNum(ev) < let numberInput = document.getElementById('page_num'); let pageNumber = parseInt(numberInput.value); if(pageNumber) < if(pageNumber = 1) < currentPageNum = pageNumber; numberInput.value =""; renderPageQueue(pageNumber); return ; >> alert("Enter a valide page numer"); > 

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