Understanding MetaMask Popups: A Deep Dive into the Code
If you’re working on building a wallet like MetaMask, you’ve probably come across the infamous “popup” feature. When you create a new MetaMask-compatible wallet or update an existing one, a pop-up window opens with a series of instructions that can seem intimidating and overwhelming at first. But what exactly is behind this behavior? In this article, we’ll dive into the MetaMask codebase to uncover the logic behind these pop-ups.
Code: A Look Under the Hood
To understand how the pop-up appears when interacting with a MetaMask-compatible wallet, let’s take a closer look at the relevant parts of the code. In particular, we’ll examine the “MetaMask” class in the Web3.js library, which is used to create and manage Ethereum accounts.
import {ether} from 'web3';
import * as MetaMask from './metaMask';
class metamask {
constructor(provider) {
this.provider = provider;
this.keypair = new ether.KeyPair();
}
async init() {
// Initialize the wallet with a standard key pair
}
async createAccount(accountName) {
// Create a new account with the MetaMask provider and the specified name
}
}
The “MetaMask” class has several methods that seem to be related to account creation, but one of these methods raises eyebrows: “createAccount”. When this method is called, the following happens:
async createAccount(accountName) {
const account = await this.init();
return new MetaMaskAccount(this.provider, account.keyPair, accountName);
}
Now let’s take a closer look at the MetaMaskAccount class.
class MetaMaskAccount extends ethers.Contract {
constructor(contracts, provider, name) {
super contracts, provider, name;
}
async createAccount(keypair, name) {
// Use the keypair to sign the transaction to create an Ethereum account
}
}
The `createAccount method in the `MetaMaskAccountservice uses a keypair object (which is created using theinitmethod ofMetaMask) to sign the transaction. When you call this method, a pop-up window opens with instructions that appear to be related to setting up an account.
Logic behind the popup
After digging a little deeper into the MetaMask code, we found several clues that could explain why the popup appears:
- Provider-specific logic: ThecreateAccount` method in MetaMaskAccount uses a provider object (specific to each MetaMask wallet) to create an account. This means that the account creation process is tied to the provider used.
- Wallet-specific data storage: When you create a new MetaMask-compatible wallet, it stores key pairs and other sensitive information in the browser’s local storage. The createAccount method likely uses this stored data to sign the transaction and create the account.
- Popup appearance
: When you call the CreateAccount method, a popup will be displayed based on MetaMask-specific instructions. These instructions may include setting up a new wallet or creating an existing wallet.
Conclusion
In summary, the pop-up window that opens when interacting with a Metamask-compatible wallet is most likely due to the provider logic and account creation processes associated with the specific provider being used. While it is not possible to modify the original code without accessing sensitive information (such as private keys), we can infer how this behavior works based on the underlying mechanics of MetaMask.
Tips for creating your own wallet
When creating your own wallet similar to MetaMask, keep the following in mind:
- Use provider logic to create accounts.
- Store key pairs and other sensitive information in local storage.
- Provide instructions that are specific to the specific wallet or account being created.
