I have a JS Array which also contains arrays with each holding a bunch of objects structured like below.
const arr1 = [
[{symbol: "xy", balance: 2155113}, {symbol: "asda", balance: 21231231}],
[{symbol: "asda", balance: 6543}, {symbol: "xy", balance: 21678}]
]What I need, is an output array, that groups all the child arrays by the "symbol" property and adds (+) the balances together.
At the End I want to have an array like this
[
{symbol: xy, summedBalance: 213131313},
{symbol: yz, summedBalance: 6788767867},
]Is this possible with normal javascript or maybe a module like lodash?
Try something like this :
const arr1 = [
[{symbol: "xy", balance: 2155113}, {symbol: "asda", balance: 21231231}],
[{symbol: "asda", balance: 6543}, {symbol: "xy", balance: 21678}]
]
// Some variables
const knownSymbolsArr = [];
const finalArr = [];
// First degroup your array
const degroupedArr = arr1.flat();
// Iterate and sum balances
degroupedArr.forEach(el => {
// Unknown symbol, process
if (knownSymbolsArr.indexOf(el.symbol) === -1) {
// Sum balances when symbol is el.symbol
const balance = degroupedArr.reduce((acc, val) => val.symbol === el.symbol ? acc + val.balance : acc, 0);
// Add symbol in our knownSymbolsArr
knownSymbolsArr.push(el.symbol);
// Add data in our final array
finalArr.push({
symbol: el.symbol,
balance: balance
});
}
});
console.log(finalArr);The solution can be broken down into two parts :
symbol and calculate the sum.const ar = [
[{symbol: "xy", balance: 2155113}, {symbol: "asda", balance: 21231231}],
[{symbol: "asda", balance: 6543}, {symbol: "xy", balance: 21678}]
]
const flattenedAr = ar.reduce((acc, curElement) => {
acc = [...acc, ...curElement];
return acc;
}, []);
const groupedAr = flattenedAr.reduce((group, curElement) => {
const matchingElement = group.find(ele => ele.symbol === curElement.symbol);
if(matchingElement) {
matchingElement.summedBalance += curElement.balance;
} else {
group.push({
symbol: curElement.symbol,
summedBalance: curElement.balance
});
}
return group
}, [])
console.log(groupedAr)