referenceerror regeneratorruntime is not defined

Referenceerror: regeneratorruntime is not defined

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In this detailed guide, we will explore the error message “Uncaught ReferenceError: regeneratorRuntime is not defined“.

At the same time, we will investigate the reasons behind this error and offer solutions to help you resolve it effectively.

This error can occur while working with JavaScript and the regenerator runtime.

Mainly, the goal is to provide you with the information and comprehension needed to troubleshoot and fix this problem promptly.

What is referenceerror regeneratorruntime is not defined?

The “ReferenceError: regeneratorRuntime is not defined” error message is commonly seen in JavaScript when utilizing async/await syntax without having the proper setup to support generators.

The error message suggests that the code refers to regeneratorRuntime, but it hasn’t been defined. This typically occurs when the necessary polyfill is absent or not correctly included in the code.

Example of Referenceerror

Here’s an example code snippet that can produce the “ReferenceError: regeneratorRuntime is not defined” error:

async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error('Error:', error);
  }
}

fetchData();

In this example, we have an async function fetchData that uses the await keyword to fetch data from an API endpoint and log it to the console.

However, if you run this code without the necessary setup for supporting generators, you will encounter the “ReferenceError: regeneratorRuntime is not defined” error.

Causes of regeneratorruntime is not defined

Generally, the causes of this error are the following:

  • Missing regenerator runtime library
  • Incorrect order of script imports
  • Incompatible environment or outdated JavaScript engine

How to fix uncaught referenceerror regeneratorruntime is not defined?

To resolve the “Uncaught ReferenceError: regeneratorRuntime is not defined” error, you need to ensure that you have the necessary setup for supporting generators and async/await syntax.

Here are a few solutions with example programs:

Solution 1: Using regenerator-runtime as a dependency (with npm and bundler)

First, we need to install the regenerator-runtime package using npm.

To do this follow and run this command:

npm install regenerator-runtime

Then, we will Import the regenerator-runtime at the entry point of your code (e.g., index.js or main.js) before using async/await syntax.

Here is the command you can try.

import 'regenerator-runtime/runtime';

Consequently, here is the example program.

// main.js
import 'regenerator-runtime/runtime';

async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error('Error:', error);
  }
}

fetchData();

Solution 2: Using a CDN (without npm or bundler)

In this case, we will include the regenerator-runtime script from a CDN in your HTML file before your other JavaScript code.

Here is the snippet code:

<script src="https://cdnjs.cloudflare.com/ajax/libs/regenerator-runtime/0.13.7/runtime.js"></script>

Thereupon, here is the example program:

<!-- index.html -->
<!DOCTYPE html>
<html>
<head>
  <title>Async/Await Example</title>
</head>
<body>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/regenerator-runtime/0.13.7/runtime.js"></script>
  <script src="script.js"></script>
</body>
</html>

<!-- script.js -->
async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error('Error:', error);
  }
}

fetchData();

Remember, both solutions ensure that the regenerator-runtime is available before the code executes, resolving the “Uncaught ReferenceError: regeneratorRuntime is not defined” error.

Take note and choose the solution that fits your development environment.

Wherein Solution 1 is suitable if you are using npm and a bundler like Webpack or Babel, while Solution 2 is suitable for simple HTML-based projects without a build process.

Asides from this error you could also check other fixed errors on this site which might help you in resolving the issues, namely:

Conclusion

To sum up the “ReferenceError: regeneratorRuntime is not defined” error can be frustrating, but with an understanding of its causes and the right solutions, you can overcome it.

By employing the appropriate tools and configuring your environment correctly, you can ensure seamless execution of async/await and generator functions in JavaScript.

We hope this article helped you address the issues.

Until next time! 😊

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