Metamask: window.ethereum undefined even on localhost [duplicate]

Metamask Window Ethereum Issue: Locally Served Web Page

As a MetaMask user, you are probably familiar with the Ethereum wallet provider’s ability to interact with your browser’s web storage and scripts. However, sometimes you run into issues when trying to access the functionality from your local development environment or a localhost server.

In this article, we’ll explore two common issues that arise when using Metamask on localhost:

• Proxy object on local development server

• Missing proxy object on locally served web page

Issue 1: Proxy object on local development server

When you run your local development environment or a localhost server, Metamask is expected to show the “window.ethereum” variable as a proxy object. This happens because MetaMask uses the browser’s “Window” object and “Ethereum” property to interact with Ethereum APIs.

Here is an example of how this might look on the local development server:

console.log(window.ethereum);
// Output: { proxy: { address: '0x...', name: 'MetaMask' } }

However, if you run your application directly from your web server (e.g. localhost:8080), the window.ethereum variable is missing. This is because the local development server is not running as a Node.js process while the localhost server is running as a web server.

To fix this issue, you can use the following workarounds:

• Run your application using Node.js: You can install Node.js on your machine and run your application using node or npx. This will allow you to access MetaMask’s functionality through window.ethereum.

• Use a different browser environment: If you are using a modern browser such as Chrome, Safari or Firefox, try running your application in a different browser environment (e.g. localhost:8080 instead of localhost:5000). This might resolve the issue due to differences in browser behavior.

Problem 2: Missing proxy object on locally served web page

When you are running your local development environment or a localhost server, Metamask is expected to show the window.ethereum variable as a proxy object. However, when you access your web page via a web browser (e.g. Chrome), this proxy does not seem to be retrieved.

Here is an example of what this might look like on the locally served web page:

console.log(window.ethereum);
// Output: undefined

The reason for this is that browsers do not execute JavaScript directly; You are running it from a web page that is run by the Node.js runtime (e.g. “node” or “npx”). Therefore, MetaMask’s functionality is not accessible through the “window.ethereum” variable.

To resolve this issue, you can use one of the following workarounds:

• Use a Node.js server: You can run your local development environment as a Node.js process and access MetaMask’s functionality directly from your web browser.

• Use a different browser environment: If you are using a modern browser such as Chrome, Safari or Firefox, try running your application in a different browser environment (e.g. “localhost:8080” instead of “localhost:5000”). This might resolve the issue due to differences in browser behavior.

Conclusion

In this article, we have explored two common issues that occur when using Metamask on localhost:

• Proxy object on local development server: The window.ethereum variable is missing or appears as an undefined value.

• Missing proxy object on locally deployed web page: MetaMask’s functionality is not accessible via the window.ethereum variable due to differences in browser behavior.

To resolve these issues, you can use workarounds such as running your application using Node.js, using a different browser environment, or accessing MetaMask’s functionality directly from your web browser.