pdf-stream

Creates a stream from PDF

Node.js module for streaming PDF text content.
Based on PDF.js library.

Table of Contents

• Install
• Usage
• API

- text(options) - new PDFReadable(options) - new PDFStringifyTransform(options)

• Contribute
• License

Install

npm i pdf-stream --save

Usage

Basic

Text stream from PDF file

'use strict';

const text = require('pdf-stream').text;

// Load file contents to ArrayBuffer synchronously
let file = './example.pdf';
let pdf = new Uint8Array(fs.readFileSync(file));

// Stream PDF text to stdout
text(pdf)
  .pipe(process.stdout);

Text stream from PDF link

You need the XMLHttpRequest as global variable. Install the xhr2 library locally:

npm i xhr2 --save

'use strict';

const text = require('pdf-stream').text;
global.XMLHttpRequest = require('xhr2'); // for PDFJS

let pdf = 'https://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf';
  
text(pdf)
  .pipe(process.stdout);

Text stream from PDF link with metadata as XML string

If you got error:

ReferenceError: DOMParser is not defined

You need the DOMParser as global variable, because PDF.js use it for XML metadata parsing. Install the xmldom library locally:

npm i xmldom --save

'use strict';

const text = require('pdf-stream').text;
global.XMLHttpRequest = require('xhr2');        // File download 
global.DOMParser = require('xmldom').DOMParser; // XML Metadata parsing

let pdf = 'https://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf';
  
text(pdf)
  .pipe(process.stdout);

Advanced

Create transform class for replacing string

'use strict';

const Transform = require('stream').Transform;
const pdf_stream = require('pdf-stream');
const PDFReadable = pdf_stream.PDFReadable;
const PDFStringifyTransform = pdf_stream.PDFStringifyTransform;

let url = 'https://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf';

// Transform class for replacing strings
class ReplaceTransform extends Transform {
  constructor(options) {
    super({
      writableObjectMode: true,
      readableObjectMode: true
    });
    this.from = options.from;
    this.to = options.to;
  }

  // For every object
  _transform(obj, encoding, cb) {
    // Get text content items
    if (typeof obj.textContent !== 'undefined'
      && Array.isArray(obj.textContent.items)) {
      obj.textContent.items.forEach((item, i) => {
        // Working with the PDF.js `textContent` object
        // Replace substring to another
        obj.textContent.items[i].str = item.str.replace(this.from, this.to);
      });
    }

    this.push(obj);
    cb();
  }

}

// Pipeline
new PDFReadable(url)
  .pipe(new ReplaceTransform({
    from: /trace/gi,
    to: ':-)'
  }))
  .pipe(new PDFStringifyTransform()) // Convert stream from object to string 
  .pipe(process.stdout);

API

All methods are streams, use them with .pipe().

text(options)

alternative usage: text(pdf, whitespace)

Gets text stream from PDF.
Convert PDF to text, optionally can replace whitespaces.
Options:

• pdf — URL or ArrayBuffer;
• whitespace — the string that replaces the whitespace ␣. Replacement disabled by default.

In the PDF.js viewer whitespaces is an empty string. For making output comparable with the viewer use: text(pdf, '')

Return: {stream.Readable}

new PDFReadable(options)

alternative usage: new PDFReadable(pdf)

Making the Readable stream in object mode from PDF text content.
Options:

• pdf — URL or ArrayBuffer;
• inherit from stream.Readable options.

Return: {stream.Readable}

new PDFStringifyTransform(options)

alternative usage: new PDFStringifyTransform(whitespace)

Transform PDF text content object to string.
Options:

• whitespace — the string that replaces the whitespace ␣. Replacement disabled by default;
• inherit from stream.Transform options.

Return: {stream.Readable}

Contribute

Contributors are welcome. Open an issue or submit pull request.
Small note: If editing the README, please conform to the standard-readme specification.

License

Apache 2.0
© Sergey N