Starting a Teleportation

Fees

As with all bridges, Teleport charges a small fee on amounts bridged between supported domains. This fee can be checked from the SDK by calling TeleportBridge.getAmounts. This function returns an object with the following structure:

{
    mintable: BigNumber,  // the amount of DAI that can be minted on the destination domain
    bridgeFee: BigNumber, // the amount of DAI that will be paid as a bridging fee
    relayFee: BigNumber,  // optional - the amount of DAI that will be paid to the relayer service, if applicable
}

The bridgeFee is set by Maker Governance, and at the time of writing it is set at 1 basis point (0.01%).

Initiating a Teleportation

To initiate a teleportation, two calls have to be made:

1. Approve the spending of DAI to the gateway contract
2. Initiate the teleportation

To achieve this, the SDK exposes two functions: TeleportBridge.approveSrcGateway and TeleportBridge.initTeleport.
These functions:

• Set up allowances for L2 DAI
• Initiate teleportation
  • Burn the L2 DAI in the Gateway contract.
  • Retrieve the generated TeleportGUID event

Both of these functions' sender parameters must be an ethers.js Signer. The SDK does not accept SignerOrProvider in its constructor, meaning that this is where you would pass it in.

initTeleport will return a promise to a transaction object that you will need to utilise for the next step. This transaction object can be used to

• wait for the transaction to pass by calling tx?.wait()
• retrieve the transaction hash tx?.hash