please avoid this pattern, it's not the first time:

if (true) {
  return true;
} else {
  return false;
}

Just return from the expression

why is that ? the parse function is your own code

can you explain why there is no xec tx for the genesis ?

no need for a special SLP_DUST const, just use DUST_AMOUNT_SATOSHIS

cashtab's novel use of 550 for dust and 546 for slp dust is not really a best practice. Just easier to have 550 vs 546 as a public facing constant.

since we already have an object input here, make this part of tokenObj

slpToken.amount is a string though -- it used to be long but this was cumbersome to handle in javascript front ends.

For slpToken.amount -- it used to be type long, and is now a string, because it's pretty common to exceed javascript's safe number limits when dealing with SLP quantities. You need some sort of BigNumber library.

You can use javascript's native BigInt, or a library if you believe this is the best way to handle it.

Cashtab uses bignumber.js which is pretty easy but not the most lightweight option. imo it's probably best to use BigInt with helper string-manipulation functions to get the decimal right (BigInt will not handle decimals).

In Ethereum, all the JS apps use https://www.npmjs.com/package/bn.js because it is already a dependency of https://www.npmjs.com/package/ethers and/or other ETH JS libraries. In our case, bn.js is already a dependency of utxo-lib

So -- we should use bn.js or javascripts native BigInt

Because bn.js is

• relatively lightweight
• already a commonly used dependency in crypto-land and thus well documented and tested
• includes more useful features compared to BigInt

this is probably the correct library to use.

slpRemainder is a BN here, use BN comparison methods

We don't want to return an BN values. Return string

Let's keep the token associated logic in the token logic function.

Instead of taking tokenAction as an optional param, getInputUtxos should take outputCount as an optional param -- defaulting to 2

Then we can determine the appropriate output count in getSlpInputUtxos

There is an available isNeg method in BN.js

See

https://www.npmjs.com/package/bn.js?activeTab=readme

Don't create BN(tokenObj.tokenSendAmount) at each loop increment as it's a constant

The would also save that one

While looking at why this is used for I noticed your fee computation is expecting all p2pkh, which an op_return is obviously not.
So your fee computation is wrong.