How to merge duplicates in an array of objects and sum a specific property? [duplicate]
You could use a hash table and generate a new array with the sums, you need.
var arr = [{ name: 'John', contributions: 2 }, { name: 'Mary', contributions: 4 }, { name: 'John', contributions: 1 }, { name: 'Mary', contributions: 1 }],
result = [];
arr.forEach(function (a) {
if (!this[a.name]) {
this[a.name] = { name: a.name, contributions: 0 };
result.push(this[a.name]);
}
this[a.name].contributions += a.contributions;
}, Object.create(null));
console.log(result);