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Sum JavaScript arrays repeated value
Suppose, we have an array of objects like this −
const arr = [ {'TR-01':1}, {'TR-02':3}, {'TR-01':3}, {'TR-02':5}];We are required to write a JavaScript function that takes in one such array and sums the value of all identical keys together.
Therefore, the summed array should look like −
const output = [ {'TR-01':4}, {'TR-02':8}];Example
The code for this will be −
const arr = [ {'TR-01':1}, {'TR-02':3}, {'TR-01':3}, {'TR-02':5}];
const sumDuplicate = arr => {
const map = {};
for(let i = 0; i < arr.length; ){
const key = Object.keys(arr[i])[0];
if(!map.hasOwnProperty(key)){
map[key] = i++;
continue;
};
arr[map[key]][key] += arr[i][key];
arr.splice(i, 1);
};
};
sumDuplicate(arr);
console.log(arr);Output
And the output in the console will be −
[ { 'TR-01': 4 }, { 'TR-02': 8 } ]
Updated on: 20-Nov-2020
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