Variables are not being set inside the .then() part of a Promise? [closed]

psbt.addInput not being updated in promise. How to workaround it??

var psbt = new bitcoin.Psbt({ network: TESTNET }); var ran = [];
//grab one or multiple utxos  
getUTXO(amt_satoshi).then((utxo_arr) => {
for (let i = 0; i < utxo_arr.length; i++) {

pre_output += utxo_arr[i].value;

getTxHex(utxo_arr[i].txid).then((tx_hex) => {
  ran;
  ran.push(tx_hex);
  console.log("HEX", tx_hex);

psbt is a bitcoinjs object(transaction), addInput stays undefined.

  psbt.addInput({
    hash: utxo_arr[i].txid,
    index: i,
    nonWitnessUtxo: Buffer.from(tx_hex),
  });
});