Pivot/Transform Javascript array of objects

Question

I need help with this please. I have the following array of objects:

[
 {
 name: "A",
 id: "q1",
 history: {
 "1:2:3": {a: 0, b: 0, c: 0},
 "4:5:6": {a: 1, b: 1, c: 1},
 "7:8:9": {a: 2, b: 2, c: 2}
 }
 },
 {
 name: "B",
 id: "q2",
 history: {
 "1:2:3": {a: 3, b: 3, c: 3},
 "4:5:6": {a: 4, b: 4, c: 4},
 "7:8:9": {a: 5, b: 5, c: 5}
 }
 },
 {
 name: "C",
 id: "q3",
 history: {
 "1:2:3": {a: 6, b: 6, c: 6},
 "4:5:6": {a: 7, b: 7, c: 7},
 "7:8:9": {a: 8, b: 8, c: 8}
 }
 }
]

and I want to obtain the following result:

{
 "1:2:3": {
 "q1": {a: 0, b: 0, c: 0},
 "q2": {a: 3, b: 3, c: 3},
 "q3": {a: 6, b: 6, c: 6}
 },
 "4:5:6": {
 "q1": {a: 1, b: 1, c: 1},
 "q2": {a: 4, b: 4, c: 4},
 "q3": {a: 7, b: 7, c: 7}
 },
 "7:8:9": {
 "q1": {a: 2, b: 2, c: 2},
 "q2": {a: 5, b: 5, c: 5},
 "q3": {a: 8, b: 8, c: 8}
 }
}

I want the result to be an object with 1:2:3, 4:5:6, 7:8:9 the keys.

Some solutions please? Thank you! :)

• jfriend00: What's the 1:2:3: and 4:5:6 and 7:8:9? That's not valid Javascript syntax.
• cmarin: Sorry, edited my question!

Answer 1

It's a good example of how can one use reduce

const data = [{
 name: "A",
 id: "q1",
 history: {
 "1:2:3": {
 a: 0,
 b: 0,
 c: 0
 },
 "4:5:6": {
 a: 1,
 b: 1,
 c: 1
 },
 "7:8:9": {
 a: 2,
 b: 2,
 c: 2
 }
 }
 },
 {
 name: "B",
 id: "q2",
 history: {
 "1:2:3": {
 a: 3,
 b: 3,
 c: 3
 },
 "4:5:6": {
 a: 4,
 b: 4,
 c: 4
 },
 "7:8:9": {
 a: 5,
 b: 5,
 c: 5
 }
 }
 },
 {
 name: "C",
 id: "q3",
 history: {
 "1:2:3": {
 a: 6,
 b: 6,
 c: 6
 },
 "4:5:6": {
 a: 7,
 b: 7,
 c: 7
 },
 "7:8:9": {
 a: 8,
 b: 8,
 c: 8
 }
 }
 }
]
const result = data.reduce((acc, item) => {
 const keys = Object.keys(item.history);
 for (let key of keys) {
 acc[key] = {
 ...(acc[key] || {}),
 [item.id]: item.history[key]
 }
 }
 return acc;
}, {})
console.log(result);