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Example Strategies

Working JavaScript scripts demonstrating common usage patterns. Each example shows a specific strategy built with the TransactionBuilder. Run them with Bun:

cd js/examples && bun run <script>.js

Key Files

File What it demonstrates
js/examples/erc20_balance_transfer.js Read an ERC20 balance, then transfer that amount — the simplest descriptor chaining pattern
js/examples/approve_and_deposit.js Approve token spending, then deposit to a vault — state-changing call followed by dependent state-changing call
js/examples/multiple_swaps.js Multi-hop swap routing: read reserves, compute swap amounts, execute swaps across multiple DEXes
js/examples/uniswap_v2_reserves.js Read Uniswap V2 pair reserves via static call, chain reserve data into subsequent calls
js/examples/anvilFork.js Fork testing with Anvil — execute strategies against mainnet state
js/examples/helpers.js Shared utilities: token approvals, contract wrappers, amount parsing
js/examples/abis.js ABI definitions for common contracts (ERC20, Uniswap V2, Aave)

Common Patterns in Examples

Basic balance-read-then-transfer

const balance = builder.addCall(ERC20_ABI, token, "balanceOf", [user]);
builder.addCall(ERC20_ABI, token, "transfer", [recipient, balance]);

The simplest descriptor chaining: static call returns a value, that value becomes an argument to a subsequent state-changing call.

Multi-step with struct fields

const accountData = builder.addCall(aaveABI, pool, "getUserAccountData", [user]);
builder.addCall(aaveABI, pool, "borrow", [
  dai,
  accountData.availableBorrowsBase,  // struct field access
  2, 0, user
]);

Dynamic type with with_length

const names = builder.addCall(abi, registry, "getNames", []);
names.with_length(3);  // array of 3 items
builder.addCall(abi, registry, "setFirst", [names[0]]);  // index access

Gotchas

  • Examples assume a running Anvil fork (run_anvil.sh starts one) — they connect to localhost:8545 via ethers or viem
  • ABI files in js/examples/abis.js are hand-curated for the specific protocols used; add ABIs as needed
  • Amounts may be mainnet-dependent — examples work against forked state; adjust addresses and amounts for different chains
  • Not all examples include value transfers — check msgValues in the built output before sending ETH

See Also