javascript – Converting BN Result to Readable String or Number in Ethjs

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I'm receiving the result in BN format. How can I convert it into actual string or number? I'm using ethjs library to interact with Smart Contract.

token.totalSupply().then((totalSupply) => {
  // result <BN ...>  4500000
});

Best Answer

Once you have a BN object, you can use .toString() or .toNumber() on it.

Per the comments below, your function isn't actually receiving a BN. It's getting some sort of Results object that has a single key in it: 0. (Presumably if the function returned multiple values, there would be more keys.)

So first extract the BN from the Result:

token.totalSupply().then(result => {
  const supply = result[0];
  console.log(supply.toString());  // or .toNumber()
});

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[Ethereum] Uncaught Error: could not decode, json: cannot unmarshal array into Go value of type string(…)

I've found what i was doing wrong in my deploy process and why accessing the contract after creation with possible but would throw the error with the address.

Turns out this is not the contract ABI :

var currencyContract = web3.eth.contract([{"constant":false,"inputs":[{"name":"_addr","type":"address"}],"name":"disapprove","outputs":[],"type":"function"},{"constant":false,"inputs":[{"name":"_target","type":"address"},{"name":"_proxy","type":"address"}],"name":"isApprovedOnceFor","outputs":[{"name":"_r","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[{"name":"_proxy","type":"address"}],"name":"isApproved","outputs":[{"name":"_r","type":"bool"}],"type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_value","type":"uint256"},{"name":"_to","type":"address"}],"name":"sendCoinFrom","outputs":[{"name":"_success","type":"bool"}],"type":"function"},{"constant":false,"inputs":[{"name":"_addr","type":"address"},{"name":"_maxValue","type":"uint256"}],"name":"approveOnce","outputs":[],"type":"function"},{"constant":true,"inputs":[{"name":"_addr","type":"address"}],"name":"coinBalanceOf","outputs":[{"name":"_r","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[{"name":"_value","type":"uint256"},{"name":"_to","type":"address"}],"name":"sendCoin","outputs":[{"name":"_success","type":"bool"}],"type":"function"},{"constant":true,"inputs":[],"name":"coinBalance","outputs":[{"name":"_r","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[{"name":"_addr","type":"address"}],"name":"approve","outputs":[],"type":"function"},{"inputs":[],"type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":false,"name":"value","type":"uint256"},{"indexed":true,"name":"to","type":"address"}],"name":"CoinSent","type":"event"}]);

So the fix the issue i had to do :

var MyContract = web3.eth.contract(currencyContract.abi);

MyContract.at("0xADDRESS")

Solidity – How to Convert Hexadecimal Values into Readable Format Using JavaScript

Try this:

let EVENT = [
    {name: "PositionKey", size: 256, indexed: true },
    {name: "Opener"     , size: 160, indexed: true },
    {name: "EtherTossed", size: 256, indexed: false},
    {name: "OddEven"    , size:   8, indexed: false},
];

function decode(data) {
    let event = {};
    let index = "0x".length;
    for (let i = 0; i < EVENT.length; i++) {
        if (!EVENT[i].indexed) {
            let name = EVENT[i].name;
            let size = Math.floor(EVENT[i].size / 4);
            event[name] = web3.toBigNumber("0x" + data.substr(index, size));
            index += size;
        }
    }
    return event;
}

Best Answer

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Solidity – How to Convert Hexadecimal Values into Readable Format Using JavaScript

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