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Created January 11, 2019 16:04
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How to set up web3.js (Ethereum JS API) with Create React Native App

How to set up web3.js with CRNA

This is a simple guide to get you started with using the Ethereum Javascript API (web3.js) with the Create React Native App project. This is not an in-depth guide.

TL;DR

If you are lazy and just want to get started, I have this project ready for you. It should work out-of-the-box.

Installation guide

  1. Make sure you have Node version 6 or later installed, if not, get it on the Node website

    node --version

  2. Install Create React Native App

    npm install -g create-react-native-app

  3. Use create-react-native-app to create the project boilerplate

    create-react-native-app my-app

  4. Install node-libs-browser

    npm install --save node-libs-browser

  5. Create a file called rn-cli.config.js on the root of the project and add the following code into it:

    const extraNodeModules = require('node-libs-browser');
    
    module.exports = {
      extraNodeModules,
    };
  6. Create a file called global.js on the root of the project and add the following code into it:

    // Inject node globals into React Native global scope.
    global.Buffer = require('buffer').Buffer;
    global.process = require('process');
    
    if (typeof btoa === 'undefined') {
      global.btoa = function (str) {
        return new Buffer(str, 'binary').toString('base64');
      };
    }
    
    if (typeof atob === 'undefined') {
      global.atob = function (b64Encoded) {
        return new Buffer(b64Encoded, 'base64').toString('binary');
      };
    }
  7. Import the global.js file into your App.js file

    import './global';
  8. Install babel-preset-es2015

    npm install --save-dev babel-cli babel-preset-es2015

  9. Now we can install the web3.js api

    npm install --save web3

  10. Require the API in your App.js file

    const Web3 = require('web3');
  11. Add the following code inside your React component in App.js to get started with consuming the API. The code will print information of the latest block on the console.

    componentWillMount() {
      const web3 = new Web3(
        new Web3.providers.HttpProvider('https://mainnet.infura.io/')
      );
    
      web3.eth.getBlock('latest').then(console.log)
    }
  12. Test it

    npm start

    or

    npm run ios

    or

    npm run android

For more examples on the API usage, visit the web3.js documentation.

For a project with all this setup ready, check out my repo.

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