CODEWITHSUNDEEP
javascriptarraysangular
Junias
Junias

Reputation: 3117

Javascript: Filter Array with duplicate Dates

I´m using Angular2 and I have an array with Date-Objects (~1000). Most of the Date-Objects have got the exactly same dates (for example 2016_11_02; Dates have no hours & minutes). Normally there should be about ~10-20 different Dates in the Array.

Now i want to filter this array and delete the duplicate Dates. So in the end there should be about ~10-20 Date-Objects in the array.

Here´s the code i tried:

let uniqueArray = duplicatesArray.filter(function(elem, pos) {
            return channelEPGDates.indexOf(elem) == pos;
        });
        console.log('unique: ' + uniqueArray.length);

I know this is not correct, cause the unique-Array has the same length as the old array. But how can i compare the Dates itself in the filter-function?

Thanks so much!

Upvotes: 3

Views: 10403

Answers (4)

Nina Scholz
Nina Scholz

Reputation: 386600

You could use Set and the spread syntax ... for it.

unique = src => [...new Set(src)];


var unique = src => [...new Set(src)];
    array = ["Mike", "Matt", "Nancy", "Adam", "Jenny", "Nancy", "Carl"];

console.log(unique(array));

To get objects with unique dates, you could filter the data by using a closure over a Set and a callback for getting the part which has to be unique.

var unique = (src, fn) => src.filter((s => o => !s.has(fn(o)) && s.add(fn(o)))(new Set));
    array = [{ date: new Date('2019-11-01')}, { date: new Date('2019-11-01')}, { date: new Date('2019-11-01')}, { date: new Date('2019-11-02')}, { date: new Date('2019-11-01')}, { date: new Date('2019-11-05')}, { date: new Date('2019-11-05')}, { date: new Date('2019-11-04')}, { date: new Date('2019-11-07')}];

console.log(unique(array, ({ date }) => date.toISOString().slice(0, 10)));
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 3

Emil S. Jørgensen
Emil S. Jørgensen

Reputation: 6366

Here is a method using the built-in methods on Array.

var arr = ["John", "Jimmy", "John"];
var dArr = []; //Date array
while (dArr.length < 10000) { //Load a lot of pseudo dates
  dArr.push(
    new Date().getTime() + Math.round(Math.random() * 10)
  );
}

function arrayUnique(arr) {
  return arr.reduce(function(previousValue, currentValue) {
    if (previousValue.some(function(value, index) {
      return value === currentValue;
    }) === false) {
      previousValue.push(currentValue);
    }
    return previousValue;
  }, []);
}

console.log(arrayUnique(arr));
console.log(arrayUnique(dArr).sort());

Upvotes: -1

Gregor Menih
Gregor Menih

Reputation: 5126

I would map the dates to epoch time using the getTime method, and then map them back to Date objects.

let uniqueArray = duplicatesArray
.map(function (date) { return date.getTime() })
.filter(function (date, i, array) {
    return array.indexOf(date) === i;
 })
.map(function (time) { return new Date(time); });

Upvotes: 13

Bhupinder kumar
Bhupinder kumar

Reputation: 556

You can do with jQuery like this :

var names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];
var uniqueNames = [];
$.each(names, function(i, el){
    if($.inArray(el, uniqueNames) === -1) uniqueNames.push(el);
});

Upvotes: 0

Related Questions