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Functional Programming exercise I can't figure out

I've been looking at a problem for hours and failing to find a solution. I'm given an array of customer objects.
In each customer object is an array of friends.
In the array of friends is an object for each friend, containing some data, including a name key/value pair.
What I'm trying to solve for: I'm given this customers array and a customer's name. I need to create a function to find if this customer name is in any other customer's friend lists, and if so, return an array of those customer's names.
Below is a customer list. And as an example, one of the customers is Olga Newton. What the code should be doing is seeing that Olga Newton is a customer and is also in the friends lists of Regina and Jay, and should be returning an array of Regina and Jay.
I thought I could do this simply with a filter function, but because the friends list is an array with more objects, this is adding level of complexity for me I can't figure out.
Below is a customer array. The out put should be
['Regina', 'Jay']
and what I've gotten has either been
[{fullCustomerObj1}, {fullCustomerObj2}]
or
[ ]
What am I missing?
Here is the customer array:
var customers = [{
name: "Olga Newton",
age: 43,
balance: "$3,400",
friends: [{
id: 0,
name: "Justice Lara"
}, {
id: 1,
name: "Duke Patrick"
}, {
id: 2,
name: "Herring Hull"
}, {
id: 3,
name: "Johnnie Berg"
}]
}, {
name: "Regina",
age: 53,
balance: "$4,000",
friends: [{
id: 0,
name: "Cheryl Kent"
}, {
id: 1,
name: "Cynthia Wells"
}, {
id: 2,
name: "Gutierrez Waters"
}, {
id: 3,
name: "Olga Newton"
}]
}, {
name: "Jay",
age: 28,
balance: "$3,000",
friends: [{
id: 0,
name: "Cross Barnett"
}, {
id: 1,
name: "Raquel Haney"
}, {
id: 2,
name: "Olga Newton"
}, {
id: 3,
name: "Shelly Walton"
}]
}];

Use filter and map, please.
function friends(c, name){
return c.filter((a) => {
return a.friends.map(b => b.name).includes(name)
}).map(a => a.name);
}
console.log(friends(customers, "Olga Newton"));
// ['Regina', 'Jay']
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

We look to an array (friends[]) inside anther (customers[]), So used two for loops, the first determine witch customer will look for his friends, and the second the array will search inside, then set if statement if the cust name is inside friends[]: adding the customer name to customerFriends[] array, At the end return the customerFriends[].
let cust = "Olga Newton"; // Get the customer name who you look for his friends.
const findFriend = (cust, arrs) => { // Create findFriend function.
let customerFriends = []; // Create an array to set the result to it.
for (let i = 0; i < arrs.length; i++) { // For each Customer.
for (const arr of arrs[i].friends) { // For each Friend.
if (arr.name === cust) { // Use Strict equality to find Customer name in friends[].
customerFriends.push(arrs[i].name); // Add the customer name to the customerFriends[].
}
}
}
return customerFriends;// Return the final results.
}
console.log(findFriend(cust, customers)); // Call the function.

What is the easiest way to match/consolidate two arrays of data that have relationships? [duplicate]

This question already has answers here:
Merge 2 arrays of objects
(46 answers)
Closed 1 year ago.
Say I have two data arrays for a ticketed event. One is attendees:
[
{name: 'Jack', ticket_code: 'iGh4rT'},
{name: 'Lisa', ticket_code: 'it1ErB'}
]
The other is tickets:
[
{code: 'iGh4rT', name: 'General Admission'},
{code: 'it1ErB', name: 'VIP'}
]
Now say I want to display a table like this:
Name
Ticket Name
Jack
General Admission
Lisa
VIP
I am struggling with doing this efficiently. I can display a table with one array no problem like something like this:
for (let i = 0; i < attendees.length; i++){
const row = `<tr>
<td>${attendees[i].name}</td>
<td>${attendees[i].ticket_code}</td>
</tr>`
document.getElementById('TableBody').innerHTML += row
I need to somehow 'query' the tickets array with the code from the attendees array for that particular person, get the name of the ticket, and supplant the ticket name instead of the code.
With SQL something like this is easy, but is one able to "query" an array and get a specific property? Should I construct a whole new array with the needed info? What is the best way to do this that would work for large unordered datasets?

You could take one of your array as an object with code as key for the object and map the other array with wanted data and the previous stored data from the object.
const
attendees = [{ name: 'Jack', ticket_code: 'iGh4rT' }, { name: 'Lisa', ticket_code: 'it1ErB' }],
tickets = [{ code: 'iGh4rT', name: 'General Admission' }, { code: 'it1ErB', name: 'VIP' }],
ticketsByCode = Object.fromEntries(tickets.map(o => [o.code, o])),
table = attendees.map(({ name, ticket_code }) => [name, ticketsByCode [ticket_code].name]);
console.log(table);

try this:
let a = [
{name: 'Jack', ticket_code: 'iGh4rT'},
{name: 'Lisa', ticket_code: 'it1ErB'}
];
let b = [
{code: 'iGh4rT', name: 'General Admission'},
{code: 'it1ErB', name: 'VIP'}
];
let c = b.map(item => {
return {
tiketName: item.name,
...a.find(itemA => itemA.ticket_code == item.code)
}
});
console.log(c);

How to filter multiple properties of one array of object from the other array of object?

I am trying to solve the problem in which i have to apply multiple filters to the array of object. Let suppose I am having a larger array of object which contains the configuration property which is further an object. On other side i have small object which are the ones the user chooses to filter(based on the checkboxes). i want to compare objects made with the parent array of objects by selecting multiple values.
So in the image the user chooses multiple values(using check boxes) and based on that he needs to filter the main array of objects.So after checking the checkboxes i get childObject and i have to filter parentArray on the basis of that..... please help me with this:
childobject =
{'Bathroom': '[2,1]',
'Bedroom': '[3,2]',
'halfBathroom':'0',
'name':'[2BD-2BA,2BD-2BA-1]'}
parentArray = [
0:{},
1:{},
2:{
'property1':'____',
'property2':'_____',
'configuration':'{
bathroom: 2
bedroom: 2
created_at: "2019-03-08 20:52:52"
created_by: 264
half_bathroom: 1
id: 26
is_selected: 0
name: "2BD-2BA-1/2BA"
name_en: "2BD-2BA-1/2BA"
name_es: "2RE-2BA-1/2BA"
status: 1
updated_at: "2019-08-23 05:39:44"
}'
}
3: {},
4:{}
]

I had to update the datastructure at some points:
You had different key in child and parent (upper/lowercase + camelcase/_ writing)
Some Missing } in the parent.
In child quotationmarks for integer deleted.Missing , added.
Changing some values in cruiteria, so that there is a result.
In parent delting of 0:, 1:, 2:, 3:, 4: to get a valid array.
childArray = {
'bathroom': [2,1],
'bedroom': [3,2],
'half_bathroom':1,
'name':['2BD-2BA', '2BD-2BA-1/2BA']
};
parentArray = [
{},
{},
{
'property1':'____',
'property2':'_____',
'configuration':{
bathroom: 2,
bedroom: 2,
created_at: "2019-03-08 20:52:52",
created_by: 264,
half_bathroom: 1,
id: 26,
is_selected: 0,
name: "2BD-2BA-1/2BA",
name_en: "2BD-2BA-1/2BA",
name_es: "2RE-2BA-1/2BA",
status: 1,
updated_at: "2019-08-23 05:39:44"
},
},
{},
{}
]
let res = parentArray.filter(elem => Object.entries(childArray).every(([key,val]) => {
let conf = elem.configuration;
if (conf===undefined) return false;
if (typeof(val) === 'object') {
return val.some(crit => crit===conf[key]);
} else {
return val===conf[key];
}
}));
console.log(res);

Comparing partial objects in ramda.js

There is an equals function in Ramdajs which is totally awesome, it will provide the following:
// (1) true
R.equals({ id: 3}, { id: 3})
// (2) true
R.equals({ id: 3, name: 'freddy'}, { id: 3, name: 'freddy'})
// (3) false
R.equals({ id: 3, name: 'freddy'}, { id: 3, name: 'freddy', additional: 'item'});
How would I go about enhancing this function, or in some other way produce a true result for number 3
I would like to ignore all the properties of the rValue not present in the lValue, but faithfully compare the rest. I would prefer the recursive nature of equals remain intact - if that's possible.
I made a simple fiddle that shows the results above.

There's a constraint on equals in order to play nicely with the Fantasy Land spec that requires the symmetry of equals(a, b) === equals(b, a) to hold, so to satisfy your case we'll need to get the objects into some equivalent shape for comparison.
We can achieve this by creating a new version of the second object that has had all properties removed that don't exist in the first object.
const intersectObj = (a, b) => pick(keys(a), b)
// or if you prefer the point-free edition
const intersectObj_ = useWith(pick, [keys, identity])
const a = { id: 3, name: 'freddy' },
b = { id: 3, name: 'freddy', additional: 'item'}
intersectObj(a, b) // {"id": 3, "name": "freddy"}
Using this, we can now compare both objects according to the properties that exist in the first object a.
const partialEq = (a, b) => equals(a, intersectObj(a, b))
// again, if you prefer it point-free
const partialEq_ = converge(equals, [identity, intersectObj])
partialEq({ id: 3, person: { name: 'freddy' } },
{ id: 3, person: { name: 'freddy' }, additional: 'item'})
//=> true
partialEq({ id: 3, person: { name: 'freddy' } },
{ id: 3, person: { age: 15 }, additional: 'item'})
//=> false

Use whereEq
From the docs: "Takes a spec object and a test object; returns true if the test satisfies the spec, false otherwise."
whereEq({ id: 3, name: 'freddy' }, { id: 3, name: 'freddy', additional: 'item' })
The other way around is to develop your own version. It boils down to:
if (is object):
check all keys - recursive
otherwise:
compare using `equals`
This is recursive point-free version that handles deep objects, arrays and non-object values.
const { equals, identity, ifElse, is, mapObjIndexed, useWith, where } = R
const partialEquals = ifElse(
is(Object),
useWith(where, [
mapObjIndexed(x => partialEquals(x)),
identity,
]),
equals,
)
console.log(partialEquals({ id: 3 }, { id: 3 }))
console.log(partialEquals({ id: 3, name: 'freddy' }, { id: 3, name: 'freddy' }))
console.log(partialEquals({ id: 3, name: 'freddy' }, { id: 3, name: 'freddy', additional: 'item' }))
<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

I haven't used Ramda.js before so if there's something wrong in my answer please be free to point out.
I learned the source code of Ramda.js
In src/equals.js, is where the function you use is defined.
var _curry2 = require('./internal/_curry2');
var _equals = require('./internal/_equals');
module.exports = _curry2(function equals(a, b) {
return _equals(a, b, [], []);
});
So it simply put the function equals (internally, called _equals) into the "curry".
So let's check out the internal _equals function, it did check the length in the line 84~86:
if (keysA.length !== keys(b).length) {
return false;
}
Just comment these lines it will be true as you wish.
You can 1) just comment these 3 lines in the distributed version of Ramda, or 2) you can add your own partialEquals function to it then re-build and create your version of Ramda (which is more recommended, from my point of view). If you need any help about that, don't hesitate to discuss with me. :)

This can also be accomplished by whereEq
R.findIndex(R.whereEq({id:3}))([{id:9}{id:8}{id:3}{id:7}])

Divide a Javascript Array and subarrays In 2 arrays

I have this array:
var myArray = [
{ familyName: 'one', subfamilies:
[ { subfamilyName: 'subOne', subItems:
[ { name: 'subOne', code: '1' },
{ name: 'subTwo', code: '2' }
] }
]
},
{ familyName: 'two', subfamilies:
[ { subfamilyName: 'subTwo', subItems:
[ { name: 'subOne', code: '1' },
{ name: 'subTwo', code: '2' },
{ name: 'subTwo', code: '3' }
] }
]
}
]
I need to divide that array in two diferent arrays with the same length if possible (my real array is so much longer), but I am having some problems getting it done. I create 2 blank array and, with for sentence read all the items. First I push the subItems in one blank array, but cannot get the way to create a new subFamily in a blank array variable and then push the sutItems array.
How can be this done?
Thanks a lot in advance.

var myOtherArray = myArray.splice(myArray.length / 2 | 0);