javascript sort with no multiple entry

Question

Here is my code

var array1 = [1,1, 30, 4, 21];
array1.sort();
console.log(array1);
// expected output: Array [1, 21, 30, 4]

I want to get the result [1,4,21,30]. the sort function should have give expected result [1,1,4,21,30] it is not giving that . Furthermore what approaches should i take just to keep one "1"? as I dont want duplications

Possible duplicate of [How to sort an array of integers correctly](https://stackoverflow.com/questions/1063007/how-to-sort-an-array-of-integers-correctly) — Mohammad Usman, May 05 '18 at 11:19
[Get all unique values in an array (remove duplicates)](https://stackoverflow.com/questions/1960473/get-all-unique-values-in-an-array-remove-duplicates) — Mohammad Usman, May 05 '18 at 11:21

Abslen Char · Answer 1 · 2018-05-05T11:58:10.737

6

You can combine sort() and reduce() just take in considiration that includes do not work in IE and as you can see in the snippet below the statement

a.includes(x) ? a : [...a, x]

represent an if statement to get rid of the duplicate element and return a single value of each element

var array1 = [1,1, 30, 4, 21];
var sortedArray1 = array1.reduce((a, x) => a.includes(x) ? a : [...a, x], []).sort()
console.log(sortedArray1);
// expected output: Array [1, 21, 30, 4]

edited May 05 '18 at 11:58

answered May 05 '18 at 11:24

Abslen Char

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3
15
29

can you please edit and explain this `a.includes(x) ? a : [...a, x]` – brk May 05 '18 at 11:43
@brk it just inline if statement to remove the duplicate element – Abslen Char May 05 '18 at 11:47
1

I got that but I just feel a bit of explanation will help others – brk May 05 '18 at 11:48
@brk I did edit my answear , Thank you for your input – Abslen Char May 05 '18 at 11:58

Muhammad Usman · Accepted Answer · 2018-05-05T11:30:58.660

4

After sort you can filter your array to get rid of duplicates.

Here

var array1 = [1,1, 30, 4, 21];
array1.sort((a, b) => a - b);
var s = array1.filter(function(i, o) {
    return array1.indexOf(i) == o;
});

console.log(s)

edited May 05 '18 at 11:30

answered May 05 '18 at 11:21

Muhammad Usman

10,039
22
39

score 4 · Answer 3 · edited Jun 20 '20 at 09:12

4

ES6

You can also use new Set([]) and the Spread_syntax to get the required result.

DEMO

let arr= [1,1, 30, 4, 21];

arr = arr.sort((a,b)=>a-b);

console.log([...new Set(arr)])

.as-console-wrapper {max-height: 100% !important;top: 0;}

edited Jun 20 '20 at 09:12

Community

1
1

answered May 05 '18 at 11:41

Narendra Jadhav

10,052
15
33
44

score 2 · Answer 4 · answered May 05 '18 at 11:23

You can use sort and filter at the same time. First using sort with condition a>b will give you an array with ascending values with duplicates and using filter will remove the duplicates from the sorted array.

var array1 = [1,1, 30, 4, 21];
function sort_unique(arr) {
    return arr.sort((a, b) => a>b).filter((el,i,a) => i==a.indexOf(el));
}
var res = sort_unique(array1);
console.log(res);

I recommend to use indexOf() as includes() do not work in IE browsers

score 1 · Answer 5 · answered May 05 '18 at 11:45

After short just try to filter uniqueValues

var array1 = [1,1, 30, 4, 21];
array1.sort(function(a, b){return a-b});
var uniqueValues = [];


 $.each(array1, function(i, el){
        if($.inArray(el, uniqueValues) === -1) uniqueValues.push(el);
    });

console.log(uniqueValues);

Result Here:

javascript sort with no multiple entry

5 Answers5

ES6