Web3js – Converting Smallest Unit of ERC20 to Full Coins Without Rounding Errors

bignumbererc-20ethereumjtokensweb3js

I can just use web3's fromWei function for all token that have 18 decimal places but I'm not sure how to convert token to full token without having to worry about rounding errors.

For example convert a token with 15 decimals:

convert 12345 to 0.000000000012345 and so on.

Any help is appreciated

Best Answer

Using a library like BigNumber or BN is important in JavaScript to avoid rounding errors in the floating point representation.

Using web3.js:

> web3.toBigNumber(12345).div(10**15).toFixed()
< "0.000000000012345"

Note that when you call a smart contract from JavaScript, you'll typically get a BigNumber object back in the first place, so you can start there (e.g. result.div(10**15).toFixed()).

Related Solutions

[Ethereum] Decimals on ERC20 Tokens

The way I think about this is that the number of tokens is:

tokenSupply = tokensIActuallyWant * (10 ** decimals)

If I want 1 token with the ability to subdivide it with a precision of 2 decimal places, I represent that as 100.

Similarly if I want 1 token with the ability to subdivide that to 18 decimal places, I need to represent that as 1000000000000000000 (1 with 18 zeros).

Hope that helps.

web3.js – How to Use toWei() Function for Tokens with 2 Decimals

Try this:

function strtodec(amount,dec){
stringf = "";
for(var i=0;i<dec;i++){
stringf = stringf+"0";
}
return amount+stringf;
}

You need to call this function using this method:

strtodec(amount,'your token decimal here')

The logic is this: The function adds zeros in the amount as many as decimals you want.

Best Answer

Related Solutions

[Ethereum] Decimals on ERC20 Tokens

web3.js – How to Use toWei() Function for Tokens with 2 Decimals

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