Convert BN to number

Question

In truffle console I am executing the following statement,

result = token.balanceOf(accounts[1])

This statement returns the following output.

<BN: 8ac7230489e80000>

As suggested here, I am trying to use toNumber() and toString. But I am getting the following error.

result = token.balanceOf(accounts[1])
result.toString()
output: '[object Promise]'
result.toNumber()
TypeError: result.toNumber is not a function

You are receiving back a promise. Can you try `await`ing or using `.then` to extract the real value? — Saddy, Jan 12 '21 at 19:27
In addition to @Saddy's comment: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise — kosmos, Jan 12 '21 at 19:29

score 6 · Accepted Answer · answered Jan 12 '21 at 19:40

Based on the output it seems you get a Promise. At the moment of running the "result.toString()" command - it's still a promise that haven't been fulfilled yet.

As @Saddy mentioned in the comment, You need to wait for the promise to be fulfilled before you could use the toString() method on its value.

You should add "await" prior to the method.

See the example in truffle documentation (https://www.trufflesuite.com/docs/truffle/quickstart):

Check the metacoin balance of the account that deployed the contract:

truffle(development)> let balance = await instance.getBalance(accounts[0])
truffle(development)> balance.toNumber()

score 1 · Answer 2 · answered Feb 01 '22 at 02:33

1

like @Saddy mentioned you can do await for the promise to resolve as shown by @Ofir or do then as shown below.

truffle(development)> await instance.getBalance(accounts[0]).then(b => { return b.toNumber() })

answered Feb 01 '22 at 02:33

Jimson James

2,937
6
43
78

Convert BN to number

2 Answers2