JavaScript SDK options

The JavaScript version of MetaMask SDK takes several options. For example, you can specify options as follows:

const options = {
  injectProvider: false,
  communicationLayerPreference: 'webrtc',
};

const MMSDK = new MetaMaskSDK(options);

The following table shows the full list of options:

Option name	Type	Default value	Description
`dappMetadata`	`{name: "My Dapp", url: "https://mydapp.com"}`	`undefined`	Only required for non-web dapps (for example, React Native and Unity).
`injectProvider`	`boolean`	`true`	Doesn't inject in Node.js or React Native since the window object is unavailable.
`forceInjectProvider`	`boolean`	`false`	Forces injection even if another provider is already present on the window object.
`forceDeleteProvider`	`boolean`	`false`	Forces deletion of a provider that exists on a window.
`checkInstallationImmediately`	`boolean`	`false`	The SDK checks if MetaMask is installed when a call to `eth_requestAccounts` is made. When `true`, it checks before any call is made.
`checkInstallationOnAllCalls`	`boolean`	`false`	Normally checked when a call to `eth_requestAccounts` is made. When `true`, it checks on all calls.
`shouldShimWeb3`	`boolean`	`true`	Set as `true` if `window.web3` should be shimmed for legacy compatibility purposes.
`preferDesktop`	`boolean`	`false`	For a web dapp running on a desktop browser without a MetaMask extension, the SDK gives the option to connect with a MetaMask Mobile wallet via a QR code. When `true`, the SDK guides the user to install the MetaMask extension instead.
`openDeeplink`	`(deeplinkUrl: string) => void`	`undefined`	Platforms open deeplinks differently. For example, web: `window.open` versus React Native: `Linking.open`. This function retrieves the deeplink URL and allows developers to customize how it opens.
`getUniversalLink`	`() => string`	`undefined`	Get the universal link that is presented on the QR Code (web) and deeplinks (mobile). This makes it easier to enable users to connect with backend code.
`communicationLayerPreference`	`"socket" or "webrtc"`	`socket`	Defines the communication library that the dapp and MetaMask wallet use to communicate with each other. Waku or another similar decentralized communication layer solution coming soon.
`webRTCLib`	`WebRTC Lib`	`undefined`	Not installed on the SDK by default.
`WalletConnectInstance`	`WalletConnect Lib`	`undefined`	Connect a dapp to MetaMask using WalletConnect. Not installed by default.
`forceRestartWalletConnect`	`boolean`	`false`	Set `forceRestartWalletConnect` to `true` to kill the previous WalletConnect session and start another one.
`transports`	`['websocket', 'polling']`	`undefined`	Used to set the preference on socket.io transports to `use`.
`timer`	`BackgroundTimer`	`undefined`	Used by React Native dapps to keep the dapp alive while using `react-native-background-timer` in the background
`enableDebug`	`boolean`	`true`	Enables/disables the sending of debugging information to the socket.io server. The default is `true` for the beta version of the SDK. The default is `false` in production versions.

tip

If your project is a web dapp and injectProvider is true, then the ethereum object should be available in window.ethereum.