Onchain JS

JavaScript bridge for Ethereum — run npm packages on the BEAM via QuickBEAM. No Node.js required. Built on onchain.

Package Family

Package	Purpose	Native Deps
onchain	Core Ethereum primitives, RPC, ABI, signing	None (pure Elixir)
onchain_aave	Aave V3 protocol wrappers	None (pure Elixir)
onchain_evm	Rust NIFs: revm simulation, Solidity parsing, codegen	Rustler
onchain_js (this)	JS bridge: npm packages on the BEAM	QuickBEAM (Zig NIF)

Pick what you need — consumers who only need eth_call never compile Zig or Rust.

Installation

def deps do
  [
    {:onchain_js, "~> 0.3"}
  ]
end

Use Cases

solc-js compilation — .sol → ABI + bytecode without installing solc natively
Uniswap v3 SDK routing — optimal swap paths, price impact via @uniswap/v3-sdk
DeFiSaver recipe builder — flash loan recipes via @defisaver/sdk
Merkle proof construction — airdrop claims, storage proofs via merkletreejs
Aave math cross-validation — validate Elixir math against @aave/math-utils
1inch Fusion SDK — DEX aggregation across protocols

How It Works

QuickBEAM embeds QuickJS-NG as a Zig NIF. Each runtime is a GenServer with a persistent JavaScript context. npm_ex manages package installation without Node.js.

Discovery

The API describes itself, so an agent can learn how to call it without reading the source:

OnchainJs.describe()                  # modules and namespaces
OnchainJs.describe(:runtime)          # function list with specs
OnchainJs.describe(:runtime, :eval)   # params, kinds, defaults, return shape

Parameters are tagged by kind: :value is something you supply, :exchange_data is something you must obtain first (the runtime handle names start_link/1 as its source). Descripex.Manifest.build/1 renders the whole surface as JSON and Descripex.MCP.tools/1 renders it as MCP tool definitions.

Testing

mix test.json --quiet                          # Unit tests
mix test.json --quiet --include integration    # Integration tests (requires QuickBEAM)

License

MIT