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Array reduce used for sum. How to implement exclusions found in a different array?

February 9, 2023

I have the following object and function to sum the values of the object keys. How can I do the same thing but make sure not to include accounts in a _ignore array?

const _balances = {
  "0x000000000": 100,
  "0xCONTRACTOR": 200,
  "0xALICE": 300,
  "0xBOB": 400,
  "0xCHARLIE": 500,
};

function circulatingSupply() {
  // Total number of tokens that are currently in circulation and are held by various accounts.
  return Object.values(_balances).reduce((a, b) => a + b, 0);
}

const CS = circulatingSupply();

console.info("Circulating Supply:", CS);

So what if I had another array whose account names should not be part of array reduce sum?

const _ignore = [
  "0x000000000",
  "0xCONTRACTOR",
];

I confess array reduce is a bit overwhelming..

>Solution :

const _balances = {
  "0x000000000": 100,
  "0xCONTRACTOR": 200,
  "0xALICE": 300,
  "0xBOB": 400,
  "0xCHARLIE": 500,
};

const _ignore = [
  "0x000000000",
  "0xCONTRACTOR",
];

function circulatingSupply() {
  // Total number of tokens that are currently in circulation and are held by various accounts.
  return Object.entries(_balances).reduce((a, [key, value]) => _ignore.includes(key) ? a : a + value, 0);
}

const CS = circulatingSupply();

console.info("Circulating Supply:", CS);