require is not defined error with browserify

I'm new to browserify and trying to load npm modules in browser but I'm getting the following error:

Uncaught ReferenceError: require is not defined

I'm following the tutorial from Created javascript file with the following content:

var unique = require('uniq');

then run

npm install uniq


browserify main.js -o bundle.js

the bundle.js file is generated and I included it in my html but still getting the above error. Any ideas what am I doing wrong?

This is the content of final HTML file:

<!DOCTYPE html>

    <script src="bundle.js"></script>
    <script src="script.js"></script>


This is the content of bundle.js:

and this is script.js:

var unique = require('uniq');



The "require" function is only available in the "bundle.js" script context. Browserify will take all the script files necessary and put them into the "bundle.js" file, so you should only have to include "bundle.js" in the HTML file, not the "script.js" file.


I personally prefer to keep my library code and application code seperate. So i also create something like a bundle.js and a script.js.

there is a simple workaround, that makes this work. This is somewhere in my browserify-file:

window.require = require;

this will expose require into the "global" namespace. You can then require all you want from your script.js.

You do give up ONE advantage, though: you'll have to include all the required libraries in your browserify file. You don't get the luxury of it finding all your dependencies, then!

I fully expect people to cry "dirty hack" or "this is not how it's meant to be". Yes, maybe. But I want those files seperate. And as long as i don't include anything else that is called "require", i'll be fine, thank you very much.

Sometimes one global can make all the difference.


It seems that to run a script like that you have to use standalone on the bundle.

browserify main.js --standalone Bundle > bundle.js

After that you should have window.Bundle in bundle.js.
So at that point you should be able to access from script.js.

if you are using grunt

If you are using grunt install grunt-browserify.

npm install grunt-browserify --save-dev

And then on grunt.js Gruntfile:

// Add the task

// Add the configuration:
browserify: {
    dist: {
        options: {
            // uncomment if you use babel
            // transform: [
            //     ["babelify", { "presets": ["env"] }]
            // ],
            browserifyOptions: {
                standalone: 'Bundle'
        files: {
           "bundle.js": ["main.js"]

if you are using gulp

 // on your build task
 var bundled = browserify('main.js', { standalone: 'Bundle' })

See here for Chart.js gulp file.

if you are using babel

If you are using babel and es6 probably you are exporting your Bundle class.

// you should have something like that 

class Bundle {


export default Bundle;

So because of babel now to use Bundle you should use Bundle.default and so:

// in script.js
var bundle = new Bundle.default();

To avoid this syntax you can override Bundle with Bundle.default.

At the end of bundle.js insert:

window.Bundle = window.Bundle.default;

So now on you'll have :

// in script.js
var bundle = new Bundle();


Standalone browserify builds


Short answer: remove the script.js import

Longer answer: You are getting the error because the method requireis not defined in the browser. You shouldn't include script.js.

The idea behind Browserify is that you can split up your sources using CommonJS modules and bundle them into one file to be used in the browser. Browserify will traverse all your sources and will concatenate all required files into the bundle.


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