How to get exact tx fee

[ptc-bink]

Now I am trying to get exact transaction fee.

I find psbt.getFeeRate()

But it doesn't work and occurs errors.

Seems like you didn't define this function.

When I send btc from A to B, set 1 addinputs and 2 addoutputs.

How to calc exact fee? If any missing, plz let me know.

[jasonandjay]

What error did you encounter?

[ptc-bink]

const psbt = new Bitcon.psbt({network: testwork})

/**

much code lines of psbt.addinput and psbt.addoutput

**/

const feeRate = psbt.getFeeRate()

Just in this step to get feeRate, functions doesn't work.

[junderw]

The transaction needs to be finalized to get the final feeRate.

The fee is just the input amounts minus the output amounts. You should know it already. There is no reason to ask about it to the transaction.