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How to browserify node module ethereumjs-util

Browserify will recursively analyze all the require() calls in your app in order to build a bundle you can serve up to the browser in a single <script> tag.

More information see:

Operating system used
macOS 10.12 Sierra

Software prerequisites

  1. Install browserify.
    Type: npm install -g browserify

  2. Show all installed node modules and their versions.
    Type: npm -g ls --depth=0

    You should see:
    [email protected]

  3. Show browserify help.
    Type: browserify --help

  4. In the following example the node module "ethereumjs-util" will be browserified.
    More information about this module see:
    Ethereumjs-util is a collection of utility functions for ethereum. It can be used in node.js or can be in the browser with browserify, which will be demonstrated below.

  5. Create a project directory.
    Type: mkdir ~/ethereumjs

  6. Install the node module ethereumjs-util locally inside this folder.
    Type: cd ~/ethereumjs
    Type: npm install ethereumjs-util

    The node module ethereumjs-util is now installed in folder cd ~/ethereumjs/node_modules
    I have installed ethereumjs-util-5.1.2

    To show all installed modules and their versions inside folder ~/ethereumjs/, type:
    cd ~/ethereumjs
    npm ls --depth=0

  7. Create a file main.js inside this folder.
    Type: touch ~/ethereumjs/main.js

  8. Enter the following lines in file main.js

    module.exports = {
        Util: require('ethereumjs-util')

    The name Util is arbitrary chosen, but it is important later when calling the module in the web page.

  9. To browserify the node module ethereumjs-util, the file main.js will be used as input. Browserify will go thru the main.js and will search all attached modules (= require()). Browserify will include the source of those "required" files in a new javascript file. The new javascript file can be given any name. In our example ethereumjs-util.js. The ethereumjs-util.js will contain the ethereumjs-util sources.

    Type: browserify main.js -s EthJS > ethereumjs-util.js

    By using the flag -s you assign the global variable name "EthJS" to the module.

  10. The browserify can also transform the code.

    Using flag -d
    Type: browserify main.js -s EthJS -d > ethereumjs-util.js

    -d means include the source map information for easier debugging in the output ethereumjs-util.js. Source map information will help you for better error tracing during development proces, but it will make the output file much larger.

    To extract the source map information in a separate file:
    • Install node module exorcist: npm install -g exorcist
    • Type: browserify main.js -s EthJS -d | exorcist > ethereumjs-util.js
    • Now two files are created: ethereumjs-util.js and

  11. To use the ethereumjs-util.js inside a web page, create a html file, for example ethereumjs_util_example.html and enter the following content:

    <!DOCTYPE html>
    <title>Ethereumjs-util example</title>
    <script type="text/javascript" src="ethereumjs-util.js"></script>
    <h1>Ethereumjs-util example</h1>
    <div id="response"></div>
    var msg = 'Hello World';
    var hash = EthJS.Util.sha3(msg);
    var output = hash.toString('hex');
    document.getElementById('response').innerHTML = output;

  12. Copy the files ethereumjs_util_example.html and ethereumjs-util.js to a webserver.
    Open a browser and access the ethereumjs_util_example.html file.