This repository comprise a set of scripts that leverages BD's DEFI API. The script collection guides the creation of an application that leverages the DEFI API and has cross-chain token transfer capabilities. This example comprises cross-chain operations where the source chain is Optimism and the target chain Polygon.
This is a Typescript project. Npm as package manager and node. Tested with npm v10.2.4, node 21.5.0. We recommend using nvm for node version management.
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Install node 21.5.0 (using nvm:
nvm install 21.5.0 && nvm use 21.5.0) -
Install the dependencies with pnpm:
pnpm install. -
Copy the environment variables with
cp .env.example .env. -
Generate a Blockdaemon API Key.
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You will need a wallet (blockchain address, private keys) to interact with the blockchains. We currently support EVM blockchains - if you do not have an account or want to generate a new one you may run the script
create-walletwithnpm exec ts-node src/main/utils/create-wallet.ts. This code locally generates a wallet, including the mnemonic you will need to sign transactions. Please make sure you add funds to the generated (or the provided) address, in particular in the blockchains you are interacting with. -
Populate the variables, including your Blockdaemon API Key (BLOCKDAEMON_API_KEY), the private key that you will be using to sign transactions in the form of a mnemonic (MNEMONIC), and RECEIVER_ADDRESS (can be the same). The standard initialisation code will read and validate the entries in your
.envfile. -
Run the scripts with
npm exec ts-node src/main/scripts/SCRIPT.ts, whereSCRIPTcan be:
do-swap(performs a cross-chain token transfer from sender to receiver based on the first received route);get-approvals(gets the status of an approval)get-chains(gets the list of supported chains)get-prices(gets token prices from a wide range of blockchains)get-routes(gets a set of routes that satisfy a swap);get-status(gets the status for a transaction);get-tokens-by-tag(gets the list of supported tokens by specified tag)get-tokens(gets the list of supported tokens)get-transactions(gets the list of transactions for an address, over different chains)make-approvals(creates a spend approval for an ERC20 token)
We also have the following utility scripts, under src/main/utils:
sign-and-broadcast-transaction (utility script)(signs and broadcasts a transaction to the blockchain)create-wallet (utility script)(locally creates an EVM wallet)
For issues related to the code in this repository, please use the issues tracker.
The mnemonic phrase is required to derive the private keys needed for signing transactions. This example uses a mnemonic to:
- Generate wallet instances for both Optimism and Polygon chains
- Sign cross-chain token transfer transactions
- Broadcast signed transactions through Blockdaemon's RPC endpoints
The wallet instances (optimismWallet and polygonWallet) are created using the mnemonic and can be used with either:
- web3js library for Web3 interactions
- ethers library for Ethereum interactions
- Blockdaemon RPC API for blockchain network access
Never share your mnemonic phrase or add it to version control. Keep it secure and use it only for testing with small amounts. The mnemonic is local to your environment and is not shared with the DEFI API.
If script output is missing, enable more verbose logging by setting the logger environment variable to either “debug” or “trace.” For example, in your .env file:
LOG_LEVEL=debug
E.g., in get-transactions.ts, the “logger.debug(...)” calls will appear in your console output when you run the script. You can apply the same approach in other files to troubleshoot logging issues.
To run the scripts that perform write actions on the blockchain (namely excecuting a swap), the source chain wallet (the sender) needs to have enough funds to do the transfers. See how to top up the Metamask wallet in the official metamask page.
Contact us through email or our support page for any issues, bugs, or assistance you may need.