Syntax

exchange.IO("multicall", ...)

Batch-reads the results of multiple contract calls in a single request through the Multicall3 contract. It is suitable for batch querying balances, liquidity pool states, quotes, and other data, and can effectively reduce the number of RPC requests.


    
    
    
exchange.IO(k, calls)


    
    
    
exchange.IO(k, calls, options)

Examples

Read wallet balances and the Uniswap liquidity pool state simultaneously in a single request.


    javascript
    
    
function main() {
    var USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"
    var WETH = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"
    var POOL = "0x88e6A0c2dDD26FEEb64F039a2c41296FcB3f5640"   // Uniswap V3 USDC/WETH 0.05% pool
    var owner = exchange.IO("address")
    exchange.IO("abi", POOL, JSON.stringify([
        { type: "function", name: "slot0", stateMutability: "view", inputs: [], outputs: [
            { name: "sqrtPriceX96", type: "uint160" }, { name: "tick", type: "int24" },
            { name: "observationIndex", type: "uint16" }, { name: "observationCardinality",
                type: "uint16" },
            { name: "observationCardinalityNext", type: "uint16" }, { name: "feeProtocol",
                type: "uint8" },
            { name: "unlocked", type: "bool" }] },
        { type: "function", name: "liquidity", stateMutability: "view", inputs: [],
            outputs: [{ type: "uint128" }] }
    ]))

    // Each item is written the same way as exchange.IO("call", ...): [contract address, method,
    // ...arguments], all read in a single request
    var ret = exchange.IO("multicall", [
        [USDC, "balanceOf", owner],
        [WETH, "balanceOf", owner],
        [POOL, "slot0"],
        [POOL, "liquidity"]
    ])
    Log("USDC balance:", ret[0], "WETH balance:", ret[1])
    Log("Pool tick:", ret[2].tick, "Liquidity:", ret[3])

    // By default, if any item fails, the entire result is null; when allowFailure is true, failed
    // items are null
    var ret2 = exchange.IO("multicall", [[USDC, "decimals"], [USDC, "transfer", POOL, 1]],
        { allowFailure: true })
    Log("decimals:", ret2[0], "transfer (the caller is the Multicall3 contract, not the wallet):",
        ret2[1])
}

Returns

Type Description

array

Returns an array of results in the same order as calls. Each item is decoded the same way as with exchange.IO("call", ...). Note that the caller (msg.sender) of every sub-call is the Multicall3 contract, whereas exchange.IO("call", ...) calls from the wallet address by default, so methods that depend on the caller (such as transfer, or write methods that check the caller's balance or allowance) give different results; exchange.IO("multicall", ...) is meant for reads that do not depend on the caller.

Arguments

Name	Type	Required	Description
k	string	Yes	Function of the `exchange.IO()` function. When set to `multicall`, it indicates that the function is used to batch-read contract call results.
calls	array	Yes	Array of calls. Each item in the array has the format `[contract address, method, ...arguments]`, written in the same way as `exchange.IO("call", ...)`, where the method can also be the complete call data (calldata). `payable` calls that attach native tokens are not supported.
options	object	No	Contains optional settings: when `allowFailure` is set to `true`, failed calls return a null value; otherwise (by default), if any call fails, the entire result is a null value, and the index and reason of the failed call can be obtained through `GetLastError()`. `block` is used to specify the block to read from (defaults to `latest`; a negative number indicates an offset relative to the latest block). `multicall` is used to specify the Multicall3 contract address (defaults to `0xcA11bde05977b3631167028862bE2a173976CA11`; this contract is deployed at this address on all mainstream EVM chains).