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How to get unique date values from object array

I need to get all unique days of multiple date values in the format DD.MM.. In this example data, there are two values for the 24th of december:
const data = [
{ date: ISODate("2019-12-24T03:24:00Z") },
{ date: ISODate("2019-12-24T04:56:00Z") },
{ date: ISODate("2019-12-25T02:34:00Z") },
{ date: ISODate("2019-12-26T01:23:00Z") }
]
So the result should be
const result = [
'24.12.',
'25.12.',
'26.12.'
]
So first of all I'll map my data and split the values only for the dates:
const dates = data.map(d => d.date.toString().split('T')[0])
But how do I get the unique values and change the output format?
Update
I came up with this, but it looks very complicated...
data.map(d => {
const dateSplit = d.date.toString().split('T')[0].split('-')
return dateSplit[2] + '.' + dateSplit[1] + '.'
})
.filter((value, index, self) {
return self.indexOf(value) === index
})

It seems that ISODate returns a standard JS Date object. You can use Date.getDate() to get the day, and Date.getMonth() to get the month (0 based, so we need to add 1):
const data = [
{ date: new Date('2019-12-24T03:24:00Z') },
{ date: new Date('2019-12-24T04:56:00Z') },
{ date: new Date('2019-12-25T02:34:00Z') },
{ date: new Date('2019-12-26T01:23:00Z') }
]
const result = [...new Set(data.map(({ date: d }) =>
`${d.getDate()}.${d.getMonth() + 1}.`
))]
console.log(result)
Previous answer:
Use a regular expression to match the month and the day, and assign them to consts using destructuring. Assemble the string using template literal. Remove duplicates by assigning the values to a Set, and then spreading back to an array.
Note: Since I don't have access to the ISODate, I've removed it. I left .toString() although it's not needed in this example, but will be needed when used with ISODate.
const data = [
{ date: '2019-12-24T03:24:00Z' },
{ date: '2019-12-24T04:56:00Z' },
{ date: '2019-12-25T02:34:00Z' },
{ date: '2019-12-26T01:23:00Z' }
]
const pattern = /-([0-9]{2})-([0-9]{2})T/
const result = [...new Set(data.map(d => {
const [, mon, day] = d.date.toString().match(pattern)
return `${day}.${mon}.`;
}))]
console.log(result)

Use .filter() to filter through only values that are the first of their value.
//temporary function
const ISODate = (d) => d;
const data = [{
date: ISODate("2019-12-24T03:24:00Z")
},
{
date: ISODate("2019-12-24T04:56:00Z")
},
{
date: ISODate("2019-12-25T02:34:00Z")
},
{
date: ISODate("2019-12-26T01:23:00Z")
}
]
const dates = data.map(d => d.date.toString().split('T')[0].split("-").slice(1, 3).reverse().join(".") + ".")
console.log(dates.filter((v, i, a) => a.indexOf(v) === i));

You can do this pretty easily by using Array.reduce. Note that I converted ISODate to be Date since I don't have that class, but it should be the same concept.
const data = [
{ date: new Date("2019-12-24T03:24:00Z") },
{ date: new Date("2019-12-24T04:56:00Z") },
{ date: new Date("2019-12-25T02:34:00Z") },
{ date: new Date("2019-12-26T01:23:00Z") }
];
const result = data.reduce( (acc, curr) => {
if (acc.length > 0) {
const hasDate = acc.find(d => d.date.getMonth() === curr.date.getMonth() && d.date.getDate() === curr.date.getDate());
if (!hasDate) { acc.push(curr); }
} else {
acc.push(curr);
}
return acc;
}, []);
console.log(result);

I would use the uniq function in the Underscore.js library:
const data = [
{ date: ISODate("2019-12-24T03:24:00Z") },
{ date: ISODate("2019-12-24T04:56:00Z") },
{ date: ISODate("2019-12-25T02:34:00Z") },
{ date: ISODate("2019-12-26T01:23:00Z") }
];
let dates = _.uniq(data.map(d => d.date.toString().split('T')[0]));

A nice considerable way is:
const array = [1, 2, 6, 5,5, 5, 3, 7, 8];
const uniqueKeys = array.reduce((hashMap, value) => {
if (!hashMap[value]) {
hashMap[value] = true;
}
return hashMap;
}, {});
const uniqueValues = Object.keys(uniqueKeys);
console.log(uniqueValues);
It is nice because it iterates the array once, instead of x * x (a.k.a log(n) instead of log(n^2) as with .filter() example
const array = [1, 2, 6, 5,5, 5, 3, 7, 8];
const uniqueKeys = array.reduce((hashMap, value) => {
if (!hashMap[value]) {
hashMap[value] = true;
}
return hashMap;
}, {});
const uniqueValues = Object.keys(uniqueKeys);
console.log(uniqueValues);

Create new object based on filtered data

I need some help. I need to calculate the amount of user actions in each month of current year. I have an array of dates:
let years = ['2017', '2018', '2019']
let datesArray = [
{date: "2019-06-05", userActionsAmount: 88},
{date: "2019-06-04", userActionsAmount: 314}
]
and I have the count object
let counts = {}
then I iterate through this like that:
years.forEach(year => {
counts[year] = datesArray.filter(singleDay => singleDay.date.slice(0, -6) === year).reduce((acc, obj) => {
return acc + obj.userActionsAmount
}, 0)
})
with this code result of counts is:
{2017: 0, 2018: 0, 2019: 402} which is ok, but I need to break the date in to months, so I need something like this:
{ 2017: []},
{ 2018: []}
{ 2019: [
{ '01': 0 },
{ '02': 0 },
{ '03': 0 },
{ '04': 0 },
{ '05': 0 },
{ '06': 402 },
{ '07': 0 },
{ '08': 0 },
{ '09': 0 },
{ '10': 0 },
{ '11': 0 },
{ '12': 0 }
]}

you can do it like this:
let datesArray = [
{date: "2019-06-05", userActionsAmount: 88},
{date: "2019-06-04", userActionsAmount: 314}
]
let result={};
datesArray.forEach(dateItem=>{
let date=dateItem.date.split("-");
let year=date[0];
let month=date[1];
if(!result[year])
result[year]={};
if(!result[year][month])
result[year][month]=0;
result[year][month]+=dateItem.userActionsAmount;
})

That's basically a very simple grouping
const datesArray = [
{date: "2019-06-05", userActionsAmount: 88},
{date: "2019-06-04", userActionsAmount: 314}
];
const groupedByMonth = datesArray.reduce((a, b) => a.set(b.date.substring(0,7), ~~a.get(b.date.substring(0,7)) + b.userActionsAmount), new Map);
console.log([...groupedByMonth]);
To get it to your format, you could do something like
const yourFormat = years.map(e => ({
[e]: Array.from(groupedByMonth).filter(([k, v]) => k.substring(0,4) === e).map(([k, v]) => ({[k.substring(5,7)]: v}))
}));
then

You could create properties when needed.
Here are two solutions : one with array methods and second more explicit.
Initialization :
const monthsKeys = ["01", "02", "03","04", "05", "06", "07", "08", "09", "10", "11", "12"];
const years = ['2017', '2018', '2019'];
const datesArray = [
{date: "2019-06-05", userActionsAmount: 88},
{date: "2019-06-04", userActionsAmount: 314}
];
const counts = {};
Solution 1 :
years.forEach( y => { counts[y] = []; });
datesArray.forEach(dateCount => {
const [year, month, day] = dateCount.date.split("-");
if (counts[year].length === 0) monthsKeys.forEach(m => {counts[year].push({[m] : 0});});
counts[year][Number(month) - 1][month] += dateCount.userActionsAmount;
});
console.log(counts);
Solution 2 :
// fill counts with years
for (const y of years) {
counts[y] = [];
}
// fill counts with months and count
for (const e of datesArray) {
const splittedDate = e.date.split("-");
const year = splittedDate[0];
const month = splittedDate[1];
// create year if needed, not necessary if years array is sure
if ( ! year in counts) {
counts[year] = [];
}
// create monthes if needed
if (counts[year].length === 0) {
for (const m of monthsKeys) {
counts[year].push({[m]: 0});
}
}
// add value
counts[year][Number(month) - 1][month] += e.userActionsAmount;
}
console.log(counts)
Why an array of objects for year values (months counts) and not simply an object?

This solution has some varation from the OP's expected output, but I believe that it should fit OP's requirements. If not, it's about a step to get the output as desired...
const years = [2017, 2018, 2019]
const dates = [{
date: "2019-06-05",
userActionAmount: 88
},
{
date: "2019-06-04",
userActionAmount: 314
}
]
const transform = (years, dates) => dates.reduce(
(output, {
date,
userActionAmount,
parsedDate = new Date(date),
year = parsedDate.getFullYear(),
month = parsedDate.getMonth() + 1,
yearData = output[year]
}) =>
(yearData[month] += userActionAmount) && output,
Object.fromEntries(years.map(year => [year, Object.fromEntries(Array.from({
length: 12
}, (_, x) => [x + 1, 0]))])))
const output = transform(years, dates)
console.log(output)
// This output lets you get total amount
// of some given month in the following way:
const monthAmount = output[2019][6]
console.log (monthAmount)

Eliminate array entries based on date

I have an array of data similar to this:
var items = [
{ id: 84, "completedDate":"2019-01-26T17:45:07.895Z" },
{ id: 92, "completedDate":"2019-02-26T17:45:07.895Z" },
{ id: 123, "completedDate":"2019-03-26T17:45:07.895Z" },
{ id: 2353, "completedDate":"2019-04-26T17:45:07.895Z" }
];
I would like to return an array with only objects less than 30 days old.
I have tried to filter
var filtered = items.filter(function(item) {
return moment(item.completedDate) > moment.subtract(30, 'days');
});
Is this what I need to do, or is there a better way to do this?

You don't need moment to compare dates:
const compareDate = new Date();
compareDate.setDate(compareDate.getDate() - 30);
const filtered = items.filter(item => new Date(item.completedDate) > compareDate);

Here's a similar way to do this without moment. here we just get the current day, reset the time back to the start of the day (you may or may not need this for your use case) and then we just use plain JS date objects to compare
var items = [
{ id: 84, "completedDate":"2019-01-26T17:45:07.895Z" },
{ id: 92, "completedDate":"2019-02-26T17:45:07.895Z" },
{ id: 123, "completedDate":"2019-03-26T17:45:07.895Z" },
{ id: 2353, "completedDate":"2019-04-26T17:45:07.895Z" }
];
var thirtyDaysAgo = new Date();
thirtyDaysAgo.setHours(0, 0, 0, 0);
thirtyDaysAgo.setDate(thirtyDaysAgo.getDate() - 30);
var filtered = items.filter(function(item) {
var d = new Date(item.completedDate).getTime();
return d > thirtyDaysAgo;
});
console.log(filtered);
Or, an even smaller filter function (if you don't need IE 11 support) would be:
var filtered = items.filter((item) => new Date(item.completedDate).getTime() > thirtyDaysAgo);

try
items.filter( x=> x.completedDate > today.toISOString() );
var items = [
{ id: 84, "completedDate":"2019-01-26T17:45:07.895Z" },
{ id: 92, "completedDate":"2019-02-26T17:45:07.895Z" },
{ id: 123, "completedDate":"2019-03-26T17:45:07.895Z" },
{ id: 2353, "completedDate":"2019-04-26T17:45:07.895Z" }
];
var today = new Date("2019-04-20T17:45:07.895Z") // or: new Date()
today = new Date(+today - 30 *86400000)
let r= items.filter( x=> x.completedDate > today.toISOString() );
console.log(r);

How to compare 3 different arrays in PHP laravel or Java Script

I have three different arrays. First array
$years = [2015,2016,2017,2018];
Second array
$users = ["a","b","c"];
Third array
$data = [
{"year":2015,"user":"a","amount":100},
{"year":2016,"user":"a","amount":90},
{"year":2017,"user":"b","amount":70},
{"year":2018,"user":"c","amount":80}
];
Now I want to compare all those arrays and get the data for each user for each year i.e if a user does not exists in particular year then 0 should be inserted in that place in below format
Desired output:
{"name":"a", "data":[100,90,0,0]},
{"name":"b", "data":[0,0,70,0]},
{"name":"c", "data":[0,0,0,80]}
My code so far is
foreach($yeararray as $year)
{
foreach($usersarray as $user)
{
if($user == $data["user"]) && ($year == $data["year"]))
{
array_append($newarray, $user);
}
else
{
array_push($newarray, $user);
}
}
}
but it is not working I think my code is somewhere wrong.

You could build a new array of objects and assign the value by using indexOf for the right index.
var years = [2015, 2016, 2017, 2018],
users = ["a", "b", "c"],
data = [{ year: 2015, user: "a", amount: 100 }, { year: 2016, user: "a", amount: 90 }, { year: 2017, user: "b", amount: 70 }, { year: 2018, user: "c", amount: 80 }],
result = users.map(user => ({ user, years: years.map(_ => 0) }));
data.forEach(({ year, user, amount }) => result[users.indexOf(user)].years[years.indexOf(year)] = amount);
console.log(result);

Iterate over the users array and retrieve the desired result. Note that adding a new user (d), justs returns an array of zeros:
var data = [
{"year":2015,"user":"a","amount":100},
{"year":2016,"user":"a","amount":90},
{"year":2017,"user":"b","amount":70},
{"year":2018,"user":"c","amount":80}
];
var years = [2015,2016,2017,2018];
var users = ["a","b","c","d"]; // Added an extra user just for the demonstration
// Iterate users
var result = users.map(function(user) {
var thisData = [];
// Iterate years
for (var i in years) {
var item = 0;
// Filter out the item for specific year and user
var rec = data.filter(function(dt) {
return dt.year == years[i] && dt.user == user;
});
if (rec.length === 1) {
item = rec[0].amount;
}
thisData.push(item);
}
return {
name: user,
data: thisData
};
});
console.log(result);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

let users = ["a", "b", "c"];
let year = [2015, 2016, 2017, 2018];
let data = [
{"year":2015,"user":"a","amount":100},
{"year":2016,"user":"a","amount":90},
{"year":2017,"user":"b","amount":70},
{"year":2018,"user":"c","amount":80}
];
let answer = [];
users.forEach(user => {
let dataArray = [];
year.forEach(year => {
if(data.some(dat => dat.year === year && dat.user===user)){
dataArray.push(data.find(dat => dat.year === year && dat.user===user).amount)
}else{
dataArray.push(0);
}
});
answer.push({"user": user, "data": dataArray});
});
console.log(answer);
First we loop thru users, for each of the user, we loop thru each of the year, using the current user and year, we can find existance in data Array, and finally compute the result

JavaScript: Compare dates in an array and sum the "price" for each month/year

I have a json file with multiple transactions with a date and a price attribute. Now I want to compare the dates and if they are in the same month and year I want to sum up the prices.
JSON:
transactions: [
{
date: "2017-11-17",
price: "28",
},
{
...
}
JavaScript:
request.onload = function() {
for(const transaction of request.response.transactions) {
let year = new Date(transaction.date).getFullYear();
let month = new Date(transaction.date).getMonth();
console.log(year + ' ' + month); // output: 2017-11 ...
}
};
I tried to loop over the json object but I struggle to find a solution to compare the dates.

Edit: Edited example with Object.assign instead of Object spread.
You'll need to use reduce to sum the prices. See comments for details.
const transactions = [{
date: "2017-11-17",
price: "28",
},
{
date: "2017-12-17",
price: "23",
},
{
date: "2017-11-17",
price: "12",
},
{
date: "2017-10-17",
price: "55",
},
{
date: "2017-11-17",
price: "09",
},
];
const sumTransactions = (transactions) => {
const summed = transactions.reduce((acc, current) => {
// Get the current date object
const date = new Date(current.date);
// Create your key/identifier
const key = `${date.getFullYear()}-${date.getMonth() + 1}`;
// Retreive the previous price from the accumulator
const previousPrice = acc[key]; // Might also return undefined
// Create your temp current price value, and be sure to deal with numbers.
let currentPrice = Number(current.price);
// If you had a previous value (and not undefined)
if (previousPrice) {
// Add it to our value
currentPrice += Number(previousPrice);
}
// Return the future accumulator value
return Object.assign(acc, {
[key]: currentPrice, // new values will overwrite same old values
})
}, {})
// Once we have all values, get the dates, and sort them (default: earlier first)
// Return an array of each value from the summed object to our sortedArray
const sortedArray = Object.keys(summed).sort().map((val) => {
return summed[val];
});
console.log("sortedArray", sortedArray);
};
sumTransactions(transactions);

I experimented a bit and came up with this solution:
var transactions = [
{
date: "2017-11-17",
price: "28",
},
{
date: "2017-12-17",
price: "22",
},
{
date: "2017-12-17",
price: "20",
}
]
var sumedUpDates = [];
var prices = [];
function isDateSumedUp(date) {
return sumedUpDates.indexOf(date.substring(0, 7)) !== -1;
}
function sumUpDate(date) {
var sum = 0;
transactions.forEach(t => {
if(t.date.substring(0, 7) === date.substring(0, 7)) {
sum += parseInt(t.price);
}
});
sumedUpDates.push(date.substring(0, 7));
prices.push(sum);
}
transactions.forEach(t => {
if(!isDateSumedUp(t.date)) {
sumUpDate(t.date);
}
});
var obj = {};
sumedUpDates.forEach((d, i) => obj[d] = prices[i]);
console.log(obj);

This solutions uses map to format your dates into year/month format for each object entry and then reduce to sum them by those separated dates.
const transactions = [
{date:"2017-11-17", price: "28",},
{date:"2017-12-17", price: "28",},
{date:"2017-11-17", price: "20",},
{date:"2017-12-17", price: "2",},
{date:"2017-11-17", price: "58",},
{date:"2017-11-17", price: "8",},
{date:"2017-10-17", price: "30",},
{date:"2018-11-17", price: "1",},
];
const mapper = single => {
let d = single.date.split('-');
let p = Number(single.price);
return { year: d[0], month: d[1], price: p };
}
const reducer = (group, current) => {
let i = group.findIndex(single => (single.year == current.year && single.month == current.month));
if (i == -1) {
return [ ...group, current ];
}
group[i].price += current.price;
return group;
};
const sumPrices = transactions.map(mapper).reduce(reducer, []);
console.log(sumPrices);

var array = [];
for (var i = 0; i < transactions.length; i++) {
var date = new Date(transactions[i].date);
var ym = date.getFullYear() + "-" + date.getMonth();
if (array[ym] == null) {
array[ym] = 0;
}
array[ym] += parseInt(transactions[i].price);
}
With this data
var transactions = [{
date: "2017-11-17",
price: "28",
},
{
date: "2017-12-17",
price: "5",
},
{
date: "2016-02-17",
price: "28",
},
{
date: "2015-11-17",
price: "25",
},
{
date: "2016-02-17",
price: "12",
},
{
date: "2017-11-17",
price: "50",
}
];
This will give you the sum of all of the year-months duplicates like this :
[
2017-10: 78,
2017-11: 5,
2016-1: 40,
2015-10: 25
]

Another solution is reduce:
var transactions = [
{date: "2017-11-17",price: "28"},
{date: "2017-12-17",price: "22"},
{date: "2017-12-17",price: "20"}
];
var result = transactions.reduce(function(acc, obj) {
var key = obj.date.substr(0,7);
acc[key] = (acc[key] || 0) + +obj.price;
return acc;
}, Object.create(null));
console.log(result);