npm i bitcoin-util-fee

npm i bitcoinfees-21co

'use strict'
const bitcoinfees = require('bitcoinfees-21co');
const feeutil = require('bitcoin-util-fee');

const getCurrentFees = () =>
    bitcoinfees.FeesApi.recommended().then(res => res.fastestFee)

const process = () => {
    const number_of_input = 1;
    const number_of_output = 2;
    const satoshi = feeutil.p2pkh_tx_calc_fee(number_of_input, number_of_output)
    console.log("P2PKH fee %d satoshi", satoshi)
}

getCurrentFees().then(fee => {
    feeutil.BASE_SATOSHI_PER_BYTE = fee; // initialize satoshi/byte rate
    process()
})

'use strict'
const bitcoinfees = require('bitcoinfees-21co');
const feeutil = require('bitcoin-fee-util');

const getCurrentFees = () =>
    bitcoinfees.FeesApi.recommended().then(res => res.fastestFee)

const process = () => {
    const number_of_input = 1;
    const number_of_output = 2;
    const p2sh_tx_calc_fee_2of3 = feeutil.p2sh_tx_calc_fee_create(2, 3);
    const satoshi = p2sh_tx_calc_fee_2of3(number_of_input, number_of_output)
    console.log("2of3 multisig fee %s satoshi", satoshi)
}

getCurrentFees().then(fee => {
    feeutil.BASE_SATOSHI_PER_BYTE = fee; // initialize satoshi/byte rate
    process()
})