Resource Calculation on Soroban

FeeCalc.js

var SorobanClient = require('soroban-client');

var server = new SorobanClient.Server('https://rpc-futurenet.stellar.org');

(async function main() {
    const account = await server.getAccount("GAN2NFRHWTY5ZNF6OQOWHOZWISA6HFFNFCX2XQMU4FJ5GMG36O7GJHVN");
    const fee = 100;
    const contract = new SorobanClient.Contract("CAO4K2VSHMLIKSE2PWZKD5HJH4I4VLT66T7IONQCWKTPZN2IG7GPNXQU");

    let transaction = new SorobanClient.TransactionBuilder(account, {
        fee, networkPassphrase: SorobanClient.Networks.FUTURENET
    })
        .addOperation(
            contract.call("increment")
        )
        .setTimeout(30)
        .build();


    const result = await server.simulateTransaction(transaction);
    console.log(result)

    const simulation_resp_json = await server._simulateTransaction(transaction);
    parseCost(simulation_resp_json)

})()


function parseCost(content) {
    const events = content.events.map((event) => {
        const e = SorobanClient.xdr.DiagnosticEvent.fromXDR(event, 'base64')

        if (e.event().type().name === 'diagnostic')
            return 0

        return e.toXDR().length
    })

    const events_and_return_value_size = (
        events.reduce((accumulator, currentValue) => accumulator + currentValue, 0) // events
        + Buffer.from(content.results[0].xdr, 'base64').length // return value size
    )

    const sorobanTransactionData = SorobanClient.xdr.SorobanTransactionData.fromXDR(content.transactionData, 'base64')

    console.log({
        //the first two lines are incorrect. use sorobanTransactionData instead of `cost`
        CPU_instructions: Number(content.cost.cpuInsns),
        RAM: Number(content.cost.memBytes),
        
        minResourceFee: content.minResourceFee,
        ledger_read_bytes: sorobanTransactionData.resources().readBytes(),
        ledger_write_bytes: sorobanTransactionData.resources().writeBytes(),
        ledger_entry_reads: sorobanTransactionData.resources().footprint().readOnly().length,
        ledger_entry_writes: sorobanTransactionData.resources().footprint().readWrite().length,
        events_and_return_value_size,
        transaction_size: Buffer.from(content.transactionData, 'base64').length,

    })
}