CODEWITHSUNDEEP
javascriptarraysreduce
Sebastian
Sebastian

Reputation: 47

Reduce elements in nested array

I am trying to filter an array and reduce values, but I don't know how.

So, I have a example array [["Hampton Tricep Rope", 3],["Chrome Curl" Bar,8],["Hampton Tricep Rope", 6]]

How to create a function with return [["Hampton Tricep Rope", 9],["Chrome Curl" Bar,8]] ?

Do you have any idea?

Upvotes: 3

Views: 81

Answers (3)

zb22
zb22

Reputation: 3231

You can use Array.prototype.reduce() to return an object which contains each unique name and its value.

Finally use Object.entries() to get an array with the key and value from that object.

const arr = [["Hampton Tricep Rope", 3],["Chrome Curl Bar", 8],["Hampton Tricep Rope", 6]];

const res = Object.entries(arr.reduce((acc, [name, value]) => {
 if(!acc[name]) {
   acc[name] = value;
 } else {
   acc[name] += value; 
 }
 
 return acc;
}, {}))

console.log(res);

Object.entries

Upvotes: 4

Lajos Arpad
Lajos Arpad

Reputation: 76544

var result = [];
[["Hampton Tricep Rope", 3],["Chrome Curl Bar",8],["Hampton Tricep Rope", 6]].reduce(function(res, value) {
  if (!result.filter((item) => (item[0] === value[0])).length) {
    result.push([value[0], value[1]]);
  } else {
    result.filter((item) => (item[0] === value[0]))[0][1] += value[1];
  }
  return res;
}, {});

We need an array to construct while we reduce the other, as you can see above. At each step we check whether we already have the element. If not, then we add it. Otherwise we increase it according to our needs.

Upvotes: -1

EugenSunic
EugenSunic

Reputation: 13703

You could use reduce and findIndex

const list = [
  ["Hampton Tricep Rope", 3],
  ["Chrome Curl Bar", 8],
  ["Hampton Tricep Rope", 6]
].reduce((acc, x) => {
  const index = acc.findIndex(y => y[0] === x[0]);
  if (index >= 0) {
    acc[index][1] += x[1];
    return acc;
  }
  acc.push(x);
  return acc;
}, [])

console.log(list)

Upvotes: -1

Related Questions