Count duplicates and order them in array of objects Javascript - javascript

I have the following array of objects:
[
{
id: 1,
someOtherStuff: 'abc,
Drink: { name: 'Coca-Cola', price: 2.5 }
},
{
id: 2,
someOtherStuff: 'def,
Drink: { name: 'Fanta Orange', price: 3 }
},
{
id: 3,
someOtherStuff: 'ghi,
Drink: { name: 'Sprite', price: 1.8 }
},
{
id: 6,
someOtherStuff: 'jkl,
Drink: { name: 'Coca-Cola', price: 2.5 }
},
{
id: 7,
someOtherStuff: 'mno,
Drink: { name: 'Coca-Cola', price: 2.5 }
}
]
i want to group them by duplicates like this:
[
{
count: 3,
drinkName: 'Coca-Cola',
price: 2.5
},
{
count: 1,
drinkName: 'Fanta Orange',
price: 3
},
{
count: 1,
drinkName: 'Sprite',
price: 1.8
}
]
I have tried in several ways to map a new array.But unfortunately I can't get it to work
I hope someone can help me with that


let result= {};
inputArray.map((item)=>{
let key = `${item.Drink.name}-${item.Drink.price}`;
if(result[key]){
result[key].count = result[key].count +1;
}else{
result[key] = {count:1,drinkName:item.Drink.name,price:item.Drink.price};
}
});
result = Object.values(result);

Related

Question from a beginner: Unexpected JS behavior [duplicate]

I'm trying to convert an array of objects where i return duplicated objects if the object properties quantity is greater than 1.
const objects = [
{ id: 1, name: "Scissor", price: 2, quantity: 3 },
{ id: 2, name: "Hat", price: 6.5, quantity: 1 },
{ id: 3, name: "Socks", price: 0.5, quantity: 5 },
];
// desired return
[
{ id: 1, name: "Scissor", price: 2 }
{ id: 1, name: "Scissor", price: 2 }
{ id: 1, name: "Scissor", price: 2 }
{ id: 2, name: "Hat", price: 6.5}
{ id: 3, name: "Socks", price: 0.5 }
{ id: 3, name: "Socks", price: 0.5 }
{ id: 3, name: "Socks", price: 0.5 }
{ id: 3, name: "Socks", price: 0.5 }
{ id: 3, name: "Socks", price: 0.5 }
]
My code:
const objects = [
{ id: 1, name: "Scissor", price: 2, quantity: 3 },
{ id: 2, name: "Hat", price: 6.5, quantity: 1 },
{ id: 3, name: "Socks", price: 0.5, quantity: 5 },
];
let newObjects= [];
Object.entries(objects).forEach(([key, value]) => {
for (let i=0; i < value.quantity; i++){
newObjects.push({ id: value.id, name: value.name, price: value.price})
}
});
console.log(newObjects);
So my code above does work, does return what i wanted, however i feel like there is a better/smoother and more of ES6 and beyond method. Could anyone please suggest a better way?

You could use .fill() and .flatMap().
const objects = [
{ id: 1, name: "Scissor", price: 2, quantity: 3 },
{ id: 2, name: "Hat", price: 6.5, quantity: 1 },
{ id: 3, name: "Socks", price: 0.5, quantity: 5 },
];
let newObjects = objects.flatMap(e=>
Array(e.quantity).fill({id: e.id, name: e.name, price: e.price})
);
console.log(newObjects);

You can use an array reduce along with an array fill.
The map is required only if you want to have unique references otherwise you can fill using the same object.
const objects = [
{ id: 1, name: "Scissor", price: 2, quantity: 3 },
{ id: 2, name: "Hat", price: 6.5, quantity: 1 },
{ id: 3, name: "Socks", price: 0.5, quantity: 5 },
];
const output = objects.reduce((a, c) => {
return a.concat(Array(c.quantity).fill({}).map(x=>({
id: c.id,
name: c.name,
price: c.price
})))
}, []);
console.log(output)

How to create a nested array of object from an array of objects

How Can I loop through this array of objects and change it so that the individual menu items are nested in the object menu_name?
const menus = [
{ menu_name: 'Entre', id:0 },
{
name: 'Soup',
price: 14.99,
id:1
},
{
name: 'Chips & Salsa',
price: 7.99,
id:2
},
{
name: 'Chicken Nuggets',
price: 12.99,
id:3
},
{ menu_name: 'Sides', id:4 },
{
name: 'Fries',
price: 4.99,
id:5
},
{
name: 'Drinks',
price: 2.99,
id:6
},
{
name: 'Onion Rings',
price: 5.99,
id:7
},
];
the end result should look like this for each menu_name object, where an array of menus is nested in the menu_name object
{
menu_name: 'Sides',
menu: [
{
name: 'Fries',
price: 4.99,
},
{
name: 'Drinks',
price: 2.99,
},
{
name: 'Onion Rings',
price: 5.99,
},
],
},

You can easily achieve this using reduce and object destructuring
const menus = [
{ menu_name: "Entre", id: 0 },
{
name: "Soup",
price: 14.99,
id: 1,
},
{
name: "Chips & Salsa",
price: 7.99,
id: 2,
},
{
name: "Chicken Nuggets",
price: 12.99,
id: 3,
},
{ menu_name: "Sides", id: 4 },
{
name: "Fries",
price: 4.99,
id: 5,
},
{
name: "Drinks",
price: 2.99,
id: 6,
},
{
name: "Onion Rings",
price: 5.99,
id: 7,
},
];
const result = menus.reduce((acc, curr) => {
const { menu_name } = curr;
if (menu_name) {
acc.push({ menu_name, menu: [] });
} else {
const { name, price } = curr;
acc[acc.length - 1].menu.push({ name, price });
}
return acc;
}, []);
console.log(result);

var newMenu = [];
menus.forEach(menu=>{
if(menu.menu_name){
newMenu.push({...menu, menu: []})
}else{
newMenu[newMenu.length-1].menu.push(menu)
}
});

How to first combine properties of an object then remove the duplicates in an array of objects using Javascript

I have an array of objects here:
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test2", quantity:1 },
{ id: 2, name: "test3", quantity:1 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:1 },
{ id: 5, name: "test7", quantity:1 },
{ id: 6, name: "test8", quantity:1 }
];
I want to add quantities of the duplicate objects together before removing them
So the result is:
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test3", quantity:2 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:2 },
{ id: 6, name: "test8", quantity:1 }
];
I have seen variations of it done removing duplicates using map or reduce but I haven't seen anything that can what I want to accomplish in an eloquent way without using too many loops.
I have been thinking about how to best accomplish this all day and haven't found anything, any help would be appreciated

You can use reduce with an object to store the element with each id.
const arr = [
{ id: 1, name: "test1", quantity:1 },
{ id: 2, name: "test2", quantity:1 },
{ id: 2, name: "test3", quantity:1 },
{ id: 3, name: "test4", quantity:1 },
{ id: 4, name: "test5", quantity:1 },
{ id: 5, name: "test6", quantity:1 },
{ id: 5, name: "test7", quantity:1 },
{ id: 6, name: "test8", quantity:1 }
];
const res = Object.values(
arr.reduce((acc,curr)=>{
acc[curr.id] = acc[curr.id] || {...curr, quantity: 0};
acc[curr.id].quantity += curr.quantity;
return acc;
}, {})
);
console.log(res);

const arr = [
{ id: 1, name: "test1", quantity: 1 },
{ id: 2, name: "test2", quantity: 1 },
{ id: 2, name: "test3", quantity: 1 },
{ id: 3, name: "test4", quantity: 1 },
{ id: 4, name: "test5", quantity: 1 },
{ id: 5, name: "test6", quantity: 1 },
{ id: 5, name: "test7", quantity: 1 },
{ id: 6, name: "test8", quantity: 1 }
];
var result = arr.reduce(function (r, a) {
r[a.id] = r[a.id] || { id: a.id, quantity: 0, name: a.name };
r[a.id].quantity += a.quantity;
return r;
}, Object.create(null));
console.log(JSON.stringify(result));

Using forEach loop and build object with aggregated quantity count.
const convert = (arr) => {
const res = {};
arr.forEach(({ id, ...rest }) =>
res[id] ? (res[id].quantity += 1) : (res[id] = { id, ...rest })
);
return Object.values(res);
};
const arr = [
{ id: 1, name: "test1", quantity: 1 },
{ id: 2, name: "test2", quantity: 1 },
{ id: 2, name: "test3", quantity: 1 },
{ id: 3, name: "test4", quantity: 1 },
{ id: 4, name: "test5", quantity: 1 },
{ id: 5, name: "test6", quantity: 1 },
{ id: 5, name: "test7", quantity: 1 },
{ id: 6, name: "test8", quantity: 1 },
];
console.log(convert(arr));

Moving data from 2 arrays of objects into a third array

so assume i have 2 arrays of objects...
let orders = [
{ id: 1, itemName: 'Peaches', amount: 2 },
{ id: 2, itemName: 'Mangoes', amount: 1 },
{ id: 3, itemName: 'Mangoes', amount: 10 }
];
let items = [
{ id: 1, name: 'Peaches', qty: 10 },
{ id: 2, name: 'Mangoes', qty: 3 }
];
and i want to find the list of orders for every item and put them in an array called linkedOrders, I tried the below code:
let linkedOrders = _.map(items, item => _.where(orders, { name: item.name }));
console.log(linkedOrders);
This is what I am getting:
[{ id: 1, itemName: 'Peaches', amount: 2 }],
[{ id: 2, itemName: 'Mangoes', amount: 1 },
{ id: 3, itemName: 'Mangoes', amount: 10 }]
but I want something like this:
[{'Peaches': [
{ id: 1, itemName: 'Peaches', amount: 2 }
],
'Mangoes': [
{ id: 2, itemName: 'Mangoes', amount: 1 },
{ id: 3, itemName: 'Mangoes', amount: 10 }
]],
Any help would be appreciated thanks.

You can simply do that using Array reduce method.
const result = items.reduce((result, item) => {
result.push({
[item.name]: orders.filter((order) => order.itemName === item.name)
});
return result;
}, []);
For more information on reduce, check Array​.prototype​.reduce()

filter inside forEach does no work properly when finds double objects

I try to get each object of an array and compare it to the objects of another array. If they match, remove the object from the second array.
Strange thing is that if an object is found two times in an array, that object is not filtered.
I want to compare newdata to existing. If an object of newdata has the same id and cat, it will not be in the new array.
existing is
var existing = [{
name: "John",
values_: {
id: 5,
cat: true
}
},
{name: "Jake",
values_: {
id: 3,
cat: true
}
},
{
name: "Alice",
values_: {
id: 2,
cat: false
}
}
];
newdata is
var newdata = [{
name: "Mike",
properties: {
id: 1,
cat: true
}
},
{name: "Jake",
properties: {
id: 3,
cat: true
}
},
{name: "Jake",
properties: {
id: 3,
cat: true
}
},
{
name: "Alice",
properties: {
id: 2,
cat: false
}
}
];
and my filter is
existing.forEach((existingitem, existingindex, existingfeatures) => {
newdata2 = newdata.filter(item => (
existingitem.values_.id != item.properties.id &&
existingitem.values_.cat != item.properties.cat
));
});
console.log('newdata2 - ',newdata2);
The logic thing is for newdata2 to have only Mike . The problem is that I can see Jake two times. Jake should not be there, its already in existing.
If I edit newdata like so (no doubles)
var newdata = [{
name: "Mike",
properties: {
id: 1,
cat: true
}
},
{name: "Jake",
properties: {
id: 3,
cat: true
}
} ,
{
name: "Alice",
properties: {
id: 2,
cat: false
}
}
];
I still can see Jake in newdata2. But why?
Please help me fix this. Is it my filter or the way filter works? Based on the criteria, I should only get Mike at the end. Please advice.
Thank you
var existing = [{
name: "John",
values_: {
id: 5,
cat: true
}
},
{name: "Jake",
values_: {
id: 3,
cat: true
}
},
{
name: "Alice",
values_: {
id: 2,
cat: false
}
}
];
var newdata = [{
name: "Mike",
properties: {
id: 1,
cat: true
}
},
{name: "Jake",
properties: {
id: 3,
cat: true
}
},
{name: "Jake",
properties: {
id: 3,
cat: true
}
},
{
name: "Alice",
properties: {
id: 2,
cat: false
}
}
];
existing.forEach((existingitem, existingindex, existingfeatures) => {
newdata2 = newdata.filter(item => (
existingitem.values_.id != item.properties.id &&
existingitem.values_.cat != item.properties.cat
));
});
console.log('newdata2 - ',newdata2);

... think about a filter (outer) and every (inner) based approach instead of forEach and filter - maybe that makes it easier to think about a correct implementation.
var existingItemList = [{ name: "John", values_: { id: 5, cat: true }}, { name: "Jake", values_: { id: 3, cat: true }}, { name: "Alice", values_: { id: 2, cat: false }}];
var newItemList = [{ name: "Mike", properties: { id: 1, cat: true }}, { name: "Jake", properties: { id: 3, cat: true }}, { name: "Jake", properties: { id: 3, cat: true }}, { name: "Alice", properties: { id: 2, cat: false }}];
var itemList = newItemList.filter(function (newItem) { // filter `newItem` only
return existingItemList.every(function (existingItem) { // if it does not exist
return ( // in `existingItemList`.
//(newItem.name !== existingItem.name) &&
(newItem.properties.id !== existingItem.values_.id)
);
});
});
console.log('itemList : ', itemList);
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EDIT
follow up, referring this comment of mine ...
your comparison condition just does not fit what you are really searching/looking for.
If one still assumes that the OP wants to filter a new item only if it does not already exist in another list that it is going to be compared to ...
... one has to write a matcher function that maps and compares item fields in one and the same time.
This comparator/matcher then has to be used in a way that it will filter only the very new item that does not equal any other already existing item.
This can be achieved by a slight change to the former approach from above ...
function doesExistingItemMatchBoundNewItem(existingItem) {
var newItem = this;
return (
(newItem.properties.id === existingItem.values_.id)
&& (newItem.properties.cat === existingItem.values_.cat)
);
}
var existingItemList = [{ name: "John", values_: { id: 5, cat: true }}, { name: "Jake", values_: { id: 3, cat: true }}, { name: "Alice", values_: { id: 2, cat: false }}];
var newItemList = [{ name: "Mike", properties: { id: 1, cat: true }}, { name: "Jake", properties: { id: 3, cat: true }}, { name: "Jake", properties: { id: 3, cat: true }}, { name: "Alice", properties: { id: 2, cat: false }}];
var itemList = newItemList.filter(function (newItem) {
return !existingItemList.some(doesExistingItemMatchBoundNewItem.bind(newItem));
});
console.log('itemList : ', itemList);
.as-console-wrapper { max-height: 100%!important; top: 0; }

You could take a Set and filter the known items.
var existing = [{ name: "John", values_: { id: 5, cat: true } }, { name: "Jake", values_: { id: 3, cat: true } }, { name: "Alice", values_: { id: 2, cat: false } }],
newdata = [{ name: "Mike", properties: { id: 1, cat: true } }, { name: "Jake", properties: { id: 3, cat: true } }, { name: "Jake", properties: { id: 3, cat: true } }, { name: "Alice", properties: { id: 2, cat: false } }],
eSet = new Set(existing.map(({ values_: { id, cat } }) => [id, cat].join('|'))),
result = newdata.filter(({ properties: { id, cat } }) => !eSet.has([id, cat].join('|')));
console.log(result);
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