This Javascript issue is produced by utilizing the Node.js global function require() in the browser. Since Node.js is a back-end technology, its module structure won't work in the browser.

Uncaught ReferenceError: require is not defined in Javascript can happen if your website is built using Node.js on the back-end but you're unfamiliar with front-end programming. This is not acceptable. This is because require() isn't part of the Javascript standard; it's a Node feature.

Exports are used by Node to define modules.

"exports.whatever = (your thing goes here)" and "require('your thing')" syntax are used to define modules in Node. Things can become a little confusing when switching between back-end Javascript code and front-end Javascript code.

There are still "modules" in the browser, but the syntax is different; instead of "modules," it's "import/export." To my mind, this is a far more comprehensible statement. However, I have no control over the situation.

Let's get your code fixed!

Problem: Using require() in Browser

This was something that was already known to us. That's all there is to this error. On the front-end, using require() almost always leads to problems.

Solution 1: Avoid Doing That

There you go! On the front end, simply ignore require and exports. There is a good likelihood that the node module you are using is not designed to be used in the browser. Webpack may be required if this is the case, as it bundles all the necessary files into a single file that can be used in the browser.

Solution 2: You may use the requirejs library

To utilize require(), you may want to check out the requirejs library first. Even though requirejs predates the modern import/export method (which I strongly recommend you use instead), it still works.

Solution 3: Instead, take advantage of Javascript modules (recommended)

Things are done differently now. Here is the code instead of a lengthy explanation of what it is.

Index.js

The type="module" attribute is very noteworthy. That's what enables you to use import and export functions.

foo.js

Main.js

And that's all there is to it. That's how front-end modules should be done.

Final Words

In this article, we explained what causes "Uncaught ReferenceError: require is not defined," and how to repair it. Use of require() in the front-end is the only thing I can think of as a common contributor (in the web browser). To use require() in front-end code, you'll need a 3rd-party library like requirejs, which is the most crucial notion here. You should probably use the official Javascript modules syntax of import and export, which you'll be familiar with if you've ever used webpack, even then.

All in all, thanks for reading! Read detailed articles on ITtutoria.net about this error and other errors like this. Each article on ITtutoria assists the reader in developing their skills and builds their confidence in their ability to address errors that arise on your websites.