Find through array in array field - arrays

Question

How can I find something through some arrays that also contain an array?
To be more precisely:
And I want to return from the coaches array, the id(within the coaches) that matches the username. What I've tried:
if (!(args['coach'].value === '') && (args['coach'].value !== null)) {
coachId = this.items.find(x => x.username === args.coach.value).id;
}
Basically this.items is what I've console.log before. Now it gives me undefined.
Has someone a fix for this? Thank you very much.
[
{
"id":584,
"name":"Name",
"coaches":[
{
"id":8587,
"username":"test"
},
{
"id":8589,
"username":"test1"
}
]
},
{
"id":587,
"name":"O1",
"coaches":[
]
}
]
And let s say I want to return the id 8587 when searching for the name test.

Answer 1

Combine map and find:
const array = [
[{a1: 1},
{a2: 2}
],
[{a1: 1},
{a2: 2},
{a3: 3}]
];
const element = array.map(innerArray => {
const found = innerArray.find(el => el.a1 === 1);
if (found) return found.a1;
return null;
}).find(el => el !== null);
console.log(element) // 1

Answer 2

For finding multiple matches do as follows:
const data = [{
"id": 584,
"name": "Name",
"coaches": [{
"id": 8587,
"username": "test"
},
{
"id": 8589,
"username": "test1"
}
]
},
{
"id": 587,
"name": "O1",
"coaches": [
]
}
];
const usernameToSearch = 'test1';
const foundCoachIds = data
.reduce((acc, curr) => {
// Destructure the coaches property first
const {
coaches,
...rest
} = curr;
// Check if any username matches the coach
const foundMatches = coaches.filter(x => x.username === usernameToSearch);
// If there is any found match push into accumulator
if (foundMatches.length) {
for (const foundMatch of foundMatches) {
if (acc.indexOf(foundMatch.id) === -1) {
acc.push(foundMatch.id);
}
}
}
return acc;
}, []);
console.log(foundCoachIds);

Answer 3

let y = this.items.filter(o => o.coaches.some(e => e.username === 'test'))[0]
.coaches.filter(e=>e.username === 'test')[0].id;
console.log(y);

Answer 4

const data = [
{
"id":584,
"name":"Name",
"coaches":[
{
"id":8587,
"username":"test"
},
{
"id":8589,
"username":"test1"
}
]
},
{
"id":587,
"name":"O1",
"coaches":[
]
}
];
For outer id
data.map(it => {return !!it.coaches.find(it2 => it2.username == "test") ? it.id : null}).filter(it=>!!it)
evaluates to [584]
For inner
(coaches) id:
data.map(it => it.coaches.find(it2 => it2.username == "test")).filter(it => !!it).map(it=> it.id)
returns [8587]
Just need to take the first item from these to get your answer.