I have a question for this case
Input:
data = [
{ number_1: 10, number_2: 20 },
{ number_1: 15, number_2: 5 },
{ number_1: 15, number_2: 35 },
];
Output:
dataSum = { sum_number_1: 40, sum_number_2: 60 };
I want to ask for 2 method we can use: array.reduce and array.forEach. And I see we need to transform array to an object for output. Thanks for your help.
The initial schema for Array.reduce is really up to you.
const data = [{
number_1: 10,
number_2: 20
},
{
number_1: 15,
number_2: 5
},
{
number_1: 15,
number_2: 35
},
];
const res = data.reduce((acc, {
number_1,
number_2
}) => {
acc.sum_number_1 += number_1;
acc.sum_number_2 += number_2;
return acc;
}, {
sum_number_1: 0,
sum_number_2: 0
})
console.log(res)And here's forEach
const data = [{
number_1: 10,
number_2: 20
},
{
number_1: 15,
number_2: 5
},
{
number_1: 15,
number_2: 35
},
];
const res = {
sum_number_1: 0,
sum_number_2: 0
};
data.forEach(({
number_1,
number_2
}) => {
res.sum_number_1 += number_1;
res.sum_number_2 += number_2;
})
console.log(res)Is this what you want?
data.reduce((acc, {number_1, number_2}) => {
acc.sum_number_1 += number_1;
acc.sum_number_2 += number_2;
return acc;
},{sum_number_1: 0, sum_number_2: 0})
Try like this:
data = [
{ number_1: 10, number_2: 20 },
{ number_1: 15, number_2: 5 },
{ number_1: 15, number_2: 35 },
];
const reducer = (accumulator, currentValue) => {
accumulator.sum_number_1 += currentValue.number_1;
accumulator.sum_number_2 += currentValue.number_2;
return accumulator;
};
console.log(data.reduce(reducer, { sum_number_1: 0, sum_number_2: 0 }));The reduce function is used with an initial value structured as the final object to be returned. The numbers are summed in the callback function to then return the result.
You could take a dynamic approach which sums all properties of an object.
const
data = [{ number_1: 10, number_2: 20 }, { number_1: 15, number_2: 5 }, { number_1: 15, number_2: 35 }],
result = data.reduce((r, o) => {
Object.entries(o).forEach(([k, v]) => r[k] = (r[k] || 0) + v)
return r;
});
console.log(result);
reducefor this, it overcomplicates things. (In general, if you're not doing functional programming with predefined, reusable reducer functions, don't usereduce.) You'll seereduceused a lot, almost always where the code would be simpler and clearer with a loop. I also wouldn't useforEach, I'd use afor-ofloop, butforEachcan work as well.0. Loop through the array adding the property values from each object to the values in your result object.