# Invalid opt nat argument: 0
**URL:** https://forum.dfinity.org/t/invalid-opt-nat-argument-0/25565
**Category:** JavaScript
**Created:** [December 15, 2023, 10:23am UTC](https://forum.dfinity.org/t/invalid-opt-nat-argument-0/25565 "2023-12-15T10:23:44Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@gladguy](https://forum.dfinity.org/u/gladguy)
#### Post date: [December 15, 2023, 10:23am UTC](https://forum.dfinity.org/t/invalid-opt-nat-argument-0/25565/1 "2023-12-15T10:23:44Z")
> **[Canister: ckBTC Index](https://dashboard.internetcomputer.org/canister/n5wcd-faaaa-aaaar-qaaea-cai)**
>
> Canister smart contract running on the Internet Computer blockchain.
I tried to access this method **get\_account\_transactions()** through javascript and my payload is,
here is my code, **start** is an **Opt NAT argument** and I passed 0 and I’m not sure about it.
const **transactionArg** = {
max\_results: 100,
account: {
owner: Principal.fromText(process.env.MY\_CANISTER),
subaccount: ,
},
**start: 0**
}
try {
const transactions = await **ckBtc\_Transac\_API.get\_account\_transactions(transactionArg);**
console.log(ckBtc\_Transac\_API);
console.log(“transactions”, transactions);
} catch (error) {
console.log(“error”, error);
}
}
---
### Author:  [@Vivienne](https://forum.dfinity.org/u/Vivienne)
#### Post date: [December 15, 2023, 12:47pm UTC](https://forum.dfinity.org/t/invalid-opt-nat-argument-0/25565/2 "2023-12-15T12:47:42Z")
The type is `Opt NAT`, and if you pass `0` you pass a `NAT`. You first need to wrap it in the optional type. While I don’t really know Js, I got it to work with `[0]` instead of `0` in a similar example. Can you try that?
---
### Author:  [@gladguy](https://forum.dfinity.org/u/gladguy)
#### Post date: [December 16, 2023, 2:21pm UTC](https://forum.dfinity.org/t/invalid-opt-nat-argument-0/25565/3 "2023-12-16T14:21:11Z")
Yeah worked @Vivienne