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JavaScript Replacing Object in Array with ID Number

So I have a series of objects that are pulled from an API and inputted into an array, something like such:
array = [
{id: 0, name: "First", relationship: "Friend"},
{id: 1, name: "Second", relationship: "Friend"}
]
The user is allowed to add and remove objects to the list freely (they will appear within a Vue.JS DataTable), and said user is allowed a maximum of 4 objects within the array (lets say 4 "friends")
How should I go about implementing a function that searches the existing array (say, if its populated from the API), and inputs the new object with the corresponding ID that is missing (so if the user deletes the object with the id 2, and adds another, it will search said array with objects, find the missing id 2 slot in the array, and input the object in its place)?
Previously I have gone about it via implement array.find() with conditionals to see if the array contains or does not contain the certain id value, however, it searches through each entry and can end up inserting the same object multiple times. Another method I haven't attempted yet would be having a separate map that contains ids, and then when a user removes an object, having it correspond with the map, and vice versa when adding.
Any suggestions? Thanks

Instead of an array, I'd keep an object in data. Have it keyed by id, like this:
let objects = {
0: { id: 0, name: 'name0', relationship: 'relationship0' },
1: { id: 1, name: 'name1', relationship: 'relationship1' },
}
Integer keys in modern JS will preserve insertion order, so you can think of this object as ordered. The API probably returns an array, so do this...
// in the method that fetches from the api
let arrayFromApi = [...];
this.objects = array.reduce((acc, obj) => {
acc[obj.id] = obj; // insertion order will be preserved
return acc;
}, {});
Your UI probably wants an array, so do this (refer to "array" in the markup):
computed: {
array() {
return Object.values(this.objects);
},
To create a new object, insert it in order, minding the available keys. Note this is a linear search, but with small numbers of objects this will be plenty fast
methods: {
// assumes maxId is const like 4 (or 40, but maybe not 400)
createObject(name, relationship) {
let object = { name, relationship };
for (let i=0; i< maxId; i++) {
if (!this.objects[i]) {
object.id = i;
this.objects[i] = object;
break;
}
}

try this,
let array = [
{id: 0, name: "First", relationship: "Friend"},
{id: 4, name: "Second", relationship: "Friend"},
{id: 2, name: "Second", relationship: "Friend"},
]
const addItem = (item) => {
let prevId = -1
// this is unnecessary if your array is already sorted by id.
// in this example array ids are not sorted. e.g. 0, 4, 2
array.sort((a, b) => a.id - b.id)
//
array.forEach(ob => {
if(ob.id === prevId + 1) prevId++
else return;
})
item = {...item, id: prevId + 1 }
array.splice(prevId+1, 0, item)
}
addItem({name: "x", relationship: "y"})
addItem({name: "a", relationship: "b"})
addItem({name: "c", relationship: "d"})
console.log(array)

You can simply achieve this with the help of Array.find() method along with the Array.indexOf() and Array.splice().
Live Demo :
// Input array of objects (coming from API) and suppose user deleted 2nd id object from the array.
const arr = [
{id: 0, name: "First", relationship: "Friend" },
{id: 1, name: "Second", relationship: "Friend" },
{id: 3, name: "Fourth", relationship: "Friend" }
];
// find the objects next to missing object.
const res = arr.find((obj, index) => obj.id !== index);
// find the index where we have to input the new object.
const index = arr.indexOf(res);
// New object user want to insert
const newObj = {
id: index,
name: "Third",
relationship: "Friend"
}
// Insert the new object into an array at the missing position.
arr.splice(index, 0, newObj);
// Output
console.log(arr);

How to merge an array of objects into one array and then filter out the duplicates

Firstly, I am trying to merge an array of many objects into a single array with every key in each object.
Lastly, any duplicate items in the array should be removed as well as any elements named "name".
Input:
const data = [
{
name: '10/20',
Tyler: 1,
Sonia: 0,
Pedro: 0,
},
{
name: '10/23',
Tyler: 0.5,
Sonia: 0.25,
Pedro: 0.75,
George: 0.5,
},
];
Output:
["Tyler", "Sonia", "Pedro", "George"]
This is what I've tried so far:
const mergedData = data.reduce((prev, cur) => {
const obj = cur[0];
const keys = Object.keys(obj);
const names = keys.splice(1);
return { names };
}, []);
I am trying to capture any key name other than "name" and add it to the final array. However, this is where I get stuck because I get this error, TypeError: Cannot convert undefined or null to object
Note: Objects may be different lengths, contain a mix of names, but never any duplicates.

An option is to find all keys put in a set and remove the name key
const data = [
{
name: '10/20',
Tyler: 1,
Sonia: 0,
Pedro: 0,
},
{
name: '10/23',
Tyler: 0.5,
Sonia: 0.25,
Pedro: 0.75,
George: 0.5,
},
];
const set = new Set(data.reduce((acc, i) => [...acc, ...Object.keys(i)], []));
set.delete('name');
const result = [...set];
console.log(result);

If you have access to ES6 methods, you can do this using a Set (unique values are ensured at creation) and converting it back into an array if you want through Destructuring.
data = [{name: '0', Tyler: '1', Dan: '2', Carl: '3'}, {name: '0', Tyler: '1', Dan: '2', Eric: '3', Danny: '4'}];
const output = (data) => {
let output = [];
// This makes sure you get each array and then strips just the keys as desired
data.forEach(item => {
output = output.
concat(Object.keys(item))
});
// This creates the set, strips our dups, and then spreads itself into an array
return [...new Set(output)]
// Strip out the 'name' key as needed
// NOTE: This should be a param instead of hard-coded, but this is easier to show
.filter(res => res != 'name');
}
console.log(output(data));
This should be fairly performant considering it only navigates the full array one time and each object itself shouldn't have millions of properties to cause .keys() any issues.

How to convert objects inside array to nested array JavaScript?

I have an array containing objects that every element but the last one are objects, but I want to convert them into an array of arrays and add the last element.
To be more explicit here is how I have it:
[
{ 0: [1,2], 1: [6,2], name: "" },
{ 0: [3,4], 1: [2,2], name: "" }
]
and the result I want is this one:
[
{ multipolygon: [ [1,2], [6,2] ], name: ""},
{ multipolygon: [ [3,4], [2,2] ], name: ""}
]
Each single array contained inside the original array is converted into an array of those arrays.
I have tried doing this:
const zonesArray = zones.map(el => Object.values(el)) // obj => array
const polygons = zonesArray.filter(el => el.pop()) // array without name
to get all the arrays contained inside the obj but then I realized how can I replace this into the original objects.
I have tried to modify the groupBy function found on MDN:
function groupBy(objectArray, property) {
return objectArray.reduce(function (acc, obj) {
let key = obj[property]
if (!acc[key]) {
acc[key] = []
}
acc[key].push(obj)
return acc
}, {})
}
But I can't seem to find the answer

It doesn't look like you're trying to group by a property, you're trying to transform each object in the array separately - which can be done by taking the name and the numeric properties together when mapping, then returning the shape of the new object:
const arr = [
{ 0: [1,2], 1: [6,2], name: "" },
{ 0: [3,4], 1: [2,2], name: "" }
];
const result = arr.map(({ name, ...rest }) => ({
name,
multipolygon: Object.values(rest)
}));
console.log(result);

Reduce Array of Array of Objects Using Ramda

I have an array of array of objects. I want to reduce that to an array of object and adding one more property to each object.
The sample input is:
const data = [
[
{name:"a", val:5},
{name:"b", val:10},
{name:"c", val:20},
{name:"d", val:50},
{name:"e", val:100}
],
[
{name:"a", val:0},
{name:"b", val:20},
{name:"c", val:30},
{name:"d", val:40},
{name:"e", val:10}
],
[
{name:"a", val:60},
{name:"b", val:50},
{name:"c", val:40},
{name:"d", val:70},
{name:"e", val:30}
]
];
And the Output should be:
[{name: 'a', val: 65, rank: 'si'},
{name: 'b', val: 80, rank: 'dp'},
{name: 'c', val: 90, rank: 'en'}
{name: 'd', val: 160, rank: 'fr'}]
Rank is static text means for a, it will always be "si"
How can I achieve this using ramda?

You can convert flatten all sub arrays to a single array, group by the name, and then map the groups, and reduce each group to a single object using R.mergeWithKey to add the val property. Convert back to an array using R.values, and map to add the static ranks property by name.
Note that you must create a Map or a dictionary object to take the rank by name from.
const { mergeWithKey, pipe, flatten, groupBy, prop, map, reduce, values } = R
const ranks = new Map([['a', 'si'], ['b', 'dp'], ['c', 'en'], ['d', 'fr']])
// merge deep and combine val property values
const combine = mergeWithKey((k, l, r) => k == 'val' ? l + r : r)
const mergeData = pipe(
flatten, // flatten to a single array
groupBy(prop('name')), // group by the name
map(reduce(combine, {})), // combine each group to a single object
values, // convert back to array
map(o => ({ ...o, rank: ranks.get(o.name) })), // add the static rank property
)
const data = [[{"name":"a","val":5},{"name":"b","val":10},{"name":"c","val":20},{"name":"d","val":50},{"name":"e","val":100}],[{"name":"a","val":0},{"name":"b","val":20},{"name":"c","val":30},{"name":"d","val":40},{"name":"e","val":10}],[{"name":"a","val":60},{"name":"b","val":50},{"name":"c","val":40},{"name":"d","val":70},{"name":"e","val":30}]]
const results = mergeData(data)
console.log(results)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.1/ramda.min.js" integrity="sha512-rZHvUXcc1zWKsxm7rJ8lVQuIr1oOmm7cShlvpV0gWf0RvbcJN6x96al/Rp2L2BI4a4ZkT2/YfVe/8YvB2UHzQw==" crossorigin="anonymous"></script>

Javascript, filtering array of objects and return all the unique objects

I have an array of objects, that contains properties that are objects:
let allPersons = [
{ id: "abcdefg",
name: "tom",
...
phone: {
brand: "blah"
id: "hijklm"
...
}
},
{ id: ....}, {...}, {...}
];
What I need to do is filter those objects and returning all the phones, filtering them by id so all phones returned are unique.
I tried to retrieve first all the phones:
// allPersons is the full array mentioned above
let phones = [...new Set(allPersons.map(person => person.phone))];
then I tried to return all the unique phones, but unsuccessfully:
let result = phones.map(phone => phone.id).filter((value, index, self) => self.indexOf(value) === index)
This returns only the unique ids of the phones, but I want the entire object. What can I do?
UPDATE:
phone Ids are NOT unique, e.g. nokia3310 has id 1, nokia3330 has id 2, etc: so tom and john can have the same phone and phone ids could be duplicated!

Make an object indexed by IDs instead, then take the object's values:
const phonesById = Object.fromEntries(
allPersons.map(
({ phone }) => [phone.id, phone]
)
);
const uniquePhones = Object.values(phonesById);

If you're trying to get the phone object in each object of the array, then the code below will do that for you.
It gets the phone object and stores it in a
var objArr = [
{id: "abcdefg", name: "tom", phone: {brand: "blah", id: "hijklm"}},
{id: "guidiuqwbd", name: "john", phone: {brand: "hihihih", id: "ayfva"}},
{id: "yuygeve", name: "doe", phone: {brand: "hahahah", id: "cqcqw"}}
]
var allPhoneObjects = [];
objArr.forEach(function(currObj){
var phoneObj = currObj.phone;
allPhoneObjects.push(phoneObj);
});
console.log(allPhoneObjects);

I propose you the following solution
let uniques = new Set();
const phones = allPersons.filter(({phone}) => (
uniques.has(phone.id) ? false : !!uniques.add(phone.id)
)).map(p => p.phone)
Basically, we define a Set to record ids of the phones already processed, and a filter function on the allPersons array, that returns only the phones not already in the Set. We complete with the map to extract only the portion of JSON needed
EDIT
You can use just one function on the allPersons array using the reduce function
let uniques = new Set();
const phones = allPersons.reduce( (filtered, {phone}) => {
if (!uniques.has(phone.id)) {
filtered.push(phone);
uniques.add(phone.id);
}
return filtered
}, [])