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Chain Utils

How To

The Chain classes exported by @renproject/chains provide utils for doing the following tasks:

All chains:

  • Check that an address is valid
  • Generate explorer links for addresses and transactions
  • Query an asset's number of decimals, for displaying human-readable balances
  • Get the transaction ID (as a string) from a Transaction object
  • Fetch the transaction details (a Transaction object) from a transaction ID.
  • Calculate the number of confirmations (or another measure of finality confidence) for transactions

Mint chains:

  • Get an address's balance of a ren-asset
  • Get the on-chain RenVM fees

Using these utils can allow you to easily add new chains in the future, knowing that they will provide the same interface.

Getting fee details​

To fetch the estimated fees of a burn or mint, you can call renJS.getFees, passing in the same asset and chain details:

await renJS.getFees({
    asset: "BTC",
    from: Bitcoin(),
    to: Ethereum(provider, "testnet"),
});

The returned value will have four fields:

{
    lock?: BigNumber;
    release?: BigNumber;
    mint: number;
    burn: number;
}
  • lock and release, in the asset's smallest unit, are the transaction fees subtracted from the transaction amount when RenVM is moving the asset into or out of the network's custody. For going from one mint-chain to another (not yet supported), lock and release will be undefined.
  • mint and burn are the portion of the transaction amount charged by RenVM, in BPS (1 BPS equals 0.01%).

Each chain class (Bitcoin, Ethereum, etc.) provide a common set of helper methods:

  1. await assetDecimals(asset) - returns the number of decimals used by the asset.
  2. utils.addressIsValid("miMi2VET...") - returns whether the the parameter is a valid address.

The parameters to the following depend on how the chain defines an Address and a Transaction.

  1. utils.addressExplorerLink(address) - returns a link to the address in a chain explorer.
  2. utils.transactionExplorerLink(transaction) - returns a link to the transaction in a chain explorer.
  3. utils.transactionID(transaction) - returns the hash or ID of the transaction as a string.

Transactions can be retrieved from a deposit object by taking deposit.depositDetails.transaction.

The Address and Transaction formats for various chains are:

// Same for Bitcoin forks.

type Address = string;

interface Transaction {
    readonly txHash: string;
    readonly vOut: number;
    readonly amount: number;
    readonly scriptPubKey?: string;
    readonly confirmations: number;
}