Use MetaMask SDK with JavaScript

Import MetaMask SDK into your JavaScript dapp to enable your users to easily connect to the MetaMask browser extension and MetaMask Mobile. The following instructions work for web dapps based on standard JavaScript. You can also see instructions for the following JavaScript-based platforms:

• React
  • React UI
• Pure JavaScript
• Other web frameworks
• React Native
• Node.js
• Electron

Prerequisites

• A JavaScript project set up
• MetaMask Mobile version 5.8.1 or later
• Yarn or npm

Steps

1. Install the SDK

In your project directory, install the SDK using Yarn or npm:

yarn add @metamask/sdk

or

npm i @metamask/sdk

2. Import the SDK

In your project script, add the following to import the SDK:

index.js

import { MetaMaskSDK } from "@metamask/sdk";

3. Instantiate the SDK

Instantiate the SDK using any options:

index.js

const MMSDK = new MetaMaskSDK({
  dappMetadata: {
    name: "JavaScript example dapp",
    url: window.location.href,
  },
  infuraAPIKey: process.env.INFURA_API_KEY,
  // Other options.
});

// You can also access via window.ethereum.
const ethereum = MMSDK.getProvider();

• Use dappMetadata to display information about your dapp in the MetaMask connection modal.
• Use infuraAPIKey to make read-only RPC requests from your dapp.
• Use modals to customize the logic and UI of the displayed modals.

4. Use the SDK

Use the SDK by calling any provider API methods. Always call eth_requestAccounts using request() first, since it prompts the installation or connection popup to appear.

ethereum.request({ method: "eth_requestAccounts", params: [] });

You can also call the SDK's connectAndSign method, and batch multiple JSON-RPC requests using the metamask_batch method.

Example

You can copy the full JavaScript example to get started:

index.js

import { MetaMaskSDK } from "@metamask/sdk";

const MMSDK = new MetaMaskSDK({
  dappMetadata: {
    name: "Example JavaScript Dapp",
    url: window.location.href,
  },
  infuraAPIKey: process.env.INFURA_API_KEY,
  // Other options.
});

// You can also access via window.ethereum.
const ethereum = MMSDK.getProvider();

ethereum.request({ method: "eth_requestAccounts", params: [] });

See the example JavaScript dapps in the JavaScript SDK GitHub repository for more information.