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Howto use Zenroom with React

This article is part of a series of blog posts about interacting with Zenroom inside the Javascript messy world. This is the second entry and at the end of the article you should be able to run a fancy hello world with React.

  1. Part one Zenroom in node.js
  2. Part two Zenroom in the browser
  3. Part three Zenroom in React
  4. Part four Zenroom in commonjs and ES6


We all know, React is one of the most adopted frameworks for client-side nowadays. Even if we have an open debate with Facebook that tried to undermine our project, read here the whole story, by stealing from us and take advantage for his Calibra/Libra stuff.

Anyhow having React working with WASM is not as straightforward as it seems and there are several attempts and several ways to achieve it (try to search on the web: wasm + react)

What we propose here is, in our opinion, the more pragmatic way with less steps freely inspired by

 🎮 Let’s get our hands dirty

Let’s start by creating a standard React project with the CRA tool, and add Zenroom as a dependency

$ npx create-react-app zenroom-react-test
$ cd zenroom-react-test
$ yarn add zenroom

So now we have to know that the create-react-app is not able to bundle by default the .wasm binary file, so the twearky solution to this is serving it as a static file, hence we are going to

$ cd public
$ ln -s ../node_modules/zenroom/dist/lib/zenroom.wasm .

link it in our /public folder.
This means that when we are going to start the webserver it will serve the file under /zenroom.wasm (cause we put it in the root directory)

But now our glue code (look at the previous post entry if you don’t know about the glue code) doesn’t have the correct address to resolve the binary we have to change a couple of lines in node_modules/zenroom/dist/lib/zenroom.js file.

Open the file and search for the string zenroom.wasm. Then change the lines

from this

var wasmBinaryFile = 'zenroom.wasm';
if (!isDataURI(wasmBinaryFile)) {
  wasmBinaryFile = locateFile(wasmBinaryFile);

to this

var wasmBinaryFile = '/zenroom.wasm';
if (!isDataURI(wasmBinaryFile)) {
  // wasmBinaryFile = locateFile(wasmBinaryFile);

we added an absolute path and commented the line that looks for the localFile that now is served as a public static one.

Now we can start to use our zenroom js lib per needed by editing the src/App.js that will look like:

import React from 'react';
import logo from './logo.svg';
import './App.css';

import zenroom from 'zenroom'

const keygen_contract = `rule check version 1.0.0
Scenario 'simple': Create the keypair
Given that I am known as 'Puria'
When I create the keypair
Then print my data`


function App() {
  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
          Edit <code>src/App.js</code> and save to reload.
          rel="noopener noreferrer"
          Learn React

export default App;

and now if you run the server with

$ yarn start

The expected result is

Hoorayyy!!! 🥳🥳🥳 And with this now you are able to maybe create your <Zencode> or <Zenroom> components and endless creative and secure possibilities.

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