Metamask: MetaMask detectEthereumProvider Check is connected to specific chain

Detecting Ethereum Providers with MetaMask in JavaScript

When interacting with a web application that requires authentication, especially those built using Ethereum-based platforms such as DApp providers or decentralized finance (DeFi) applications, it is crucial to ensure a seamless integration. One of the key aspects is detecting the Ethereum provider connected to a user account.

The detectEthereumProvider library from @metamask/detect-provider provides a simple way to achieve this. In this article, we will look at how you can use MetaMask in a JavaScript application to detect an Ethereum provider and then connect it to detailed on-chain information.

Configuring DetectEthereumProvider

First, you need to install the detectEthereumProvider library using npm or yarn:

npm install @metamask/detect-provider

Or using yarn:

yarn add @metamask/detect-provider

Then import and initialize the provider in your JavaScript code. Here is an example of how you can do it:

import detectEthereumProvider from '@metamask/detect-provider';
const ethereum = await detectEthereumProvider();

In this code snippet, ethereum is assigned the result of the detectEthereumProvider function call.

Connecting to a specific chain

To connect an Ethereum provider to a specific chain, you need to specify the chain details. This includes the network ID (e.g. 1 for Mainnet, 4 for Ropsten), gas price, and other optional parameters. Here is an example of how to do it:

const chainId = ethereum.chainId;
console.log(ChainId: ${chainId});
if (chainId === 1) {
// Mainnet settings
} else if (chainId === 4) {
// Ropsten network settings
}

In this example, we check the chainId property to determine which chain settings to apply. You can add more conditions if needed.

Additional parameters

The detectEthereumProvider function returns an object with several properties that you can use to customize your interaction with Ethereum:

• chainId: Network identifier.

• networkName: Network name (e.g. “Eth”, “ERC20”).

• gasPrice: Gas price in Wei (1 Wei = 1/10^15 Ether).

• maxBlockNumber: Maximum number of blocks to download.

• accounts: An array of Ethereum accounts, where each account is an object with properties like address, name.

You can access these properties using the ethereum object returned by detectEthereumProvider. For example:

const gasPrice = ethereum.gasPrice;
console.log(GasPrice: ${gasPrice});
const accounts = ethereum.accounts;
console.log("Accounts:");
accounts.forEach((account) => console.log(account));

Example use case

Here is an updated version of the code that includes a basic login system:

import detectEthereumProvider from '@metamask/detect-provider';
const ethereum = await detectEthereumProvider();
async function login() {
// Your login logic here...
}
login();

When you run this code, you will be prompted for your Ethereum provider credentials. Once the user enters the correct credentials, the ethereum object will be connected and a success message will be displayed.

By following these steps, you can successfully integrate MetaMask into your JavaScript application to detect specific Ethereum providers and connect them to different chain settings.