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Wojciech Maj edited this page Mar 30, 2020 · 9 revisions

Bundling my app with React-PDF is too slow. What can I do?

Some performance decrease after React-PDF is added to your bundle is inevitable. React-PDF uses Mozilla's PDF.js which weighs around 1800 kb before compression.

Here are several things you can do to improve this. We're using React-PDF sample page as a benchmark.

Ensure you're using the most up to date version of Node.js and bundler

Newest versions of Node.js can significantly improve performance of bundlers like Webpack. It works the other way around, too: bundlers like Webpack take advantage of some tricks Node.js can do in the newest versions. It's a good idea to keep them both up to date.

Make use of multi-process minifying in UglifyJsPlugin

With parallel option in UglifyJsPlugin, you can use multiple processor cores to do the minifying. This speeds up bundling process by quite a bit.

new webpack.optimize.UglifyJsPlugin({
+  parallel: true,
}),

Enable cache in UglifyJsPlugin

PDF.js files remain unchanged between builds, so it won't hurt to use caching to prevent UglifyJsPlugin from doing the same job over and over again. This speeds the second and all the next builds.

new webpack.optimize.UglifyJsPlugin({
+  cache: true,
}),

When I'm trying to load a PDF file from an external source, I'm given a message "Failed to load PDF file.".

If you are sure the URL to the external source you're trying to load is correct, most likely you are experiencing effects of Same-origin Policy. In order to load files from domains other than your own you can do the following:

  • Ask domain owner to include your domain in Access-Control-Allow-Origin HTTP header.
  • Use a server side-proxy that will go around Same-origin policy limitations (beware: that is a potential security issue, so be sure you know what you're doing before creating one).

Read more about CORS.

I render Document, but nothing is rendered. Why?

If you are using React-PDF like this:

<Document file="http://example.com/document.pdf" />

then nothing will be rendered. Document component only gives its children (and grandchildren, and great-grandchildren…) a "context" on PDF file you're trying to render. React-PDF can do multiple things with PDF file. You can, for example:

  • Render a page
  • Render a few pages
  • Render document's outline (Table of Contents)

so you need to specify what would you like to do. So to render a page, you need to write:

<Document file="http://example.com/document.pdf">
  <Page pageNumber={1} />
</Document>

React-PDF reloads itself with every render. What's going on?

If you are using React-PDF like this:

<Document file={{ url: 'http://example.com/document.pdf' }} />

then React-PDF thinks you're giving it new (referentially unequal) file object with every render. Try it in your browser's console!

> ({ url: 'http://example.com/document.pdf' }) === ({ url: 'http://example.com/document.pdf' })
< false // surprise!

To deal with this, you can save file object, for example, by assigning it to this when URL changes:

// Called when URL to PDF changes
onFileChange = (url) => {
  this.file = { url };
}

render() {
  return (
    <Document file={this.file} />
  );
}

This way React-PDF will get the same object with each render.

How do I load a PDF from Base64?

To open load a PDF from Base64, you need to need to transform it to Data URL. Don't worry, it's easy!

Here's a sample PDF file in Base64:

JVBERi0xLjIgCjkgMCBvYmoKPDwKPj4Kc3RyZWFtCkJULyA5IFRmKFRlc3QpJyBFVAplbmRzdHJlYW0KZW5kb2JqCjQgMCBvYmoKPDwKL1R5cGUgL1BhZ2UKL1BhcmVudCA1IDAgUgovQ29udGVudHMgOSAwIFIKPj4KZW5kb2JqCjUgMCBvYmoKPDwKL0tpZHMgWzQgMCBSIF0KL0NvdW50IDEKL1R5cGUgL1BhZ2VzCi9NZWRpYUJveCBbIDAgMCA5OSA5IF0KPj4KZW5kb2JqCjMgMCBvYmoKPDwKL1BhZ2VzIDUgMCBSCi9UeXBlIC9DYXRhbG9nCj4+CmVuZG9iagp0cmFpbGVyCjw8Ci9Sb290IDMgMCBSCj4+CiUlRU9G

all you have to do is prepend your Base64 string with data:application/pdf;base64,. It turns into a valid link. Try and paste the string below into your browser!

data:application/pdf;base64,JVBERi0xLjIgCjkgMCBvYmoKPDwKPj4Kc3RyZWFtCkJULyA5IFRmKFRlc3QpJyBFVAplbmRzdHJlYW0KZW5kb2JqCjQgMCBvYmoKPDwKL1R5cGUgL1BhZ2UKL1BhcmVudCA1IDAgUgovQ29udGVudHMgOSAwIFIKPj4KZW5kb2JqCjUgMCBvYmoKPDwKL0tpZHMgWzQgMCBSIF0KL0NvdW50IDEKL1R5cGUgL1BhZ2VzCi9NZWRpYUJveCBbIDAgMCA5OSA5IF0KPj4KZW5kb2JqCjMgMCBvYmoKPDwKL1BhZ2VzIDUgMCBSCi9UeXBlIC9DYXRhbG9nCj4+CmVuZG9iagp0cmFpbGVyCjw8Ci9Sb290IDMgMCBSCj4+CiUlRU9G

So, how to do this with React-PDF? Like so:

<Document file={`data:application/pdf;base64,${base64String}`}>
  <Page pageNumber={1} />
</Document>
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