Javascript/Jquery- new array from existing two arrays

Question

I have two arrays

 var a= $("#update-select1").val();  // gives value 1,2,4
 var b= $("#update-select2").val();  // 1,2,5

I want two different arrays from the above two arrays.

//array has the values which is in  `b` but not in `a`
var c = [5]

//another array has value in `a` but not in `b`
var d =[4]

You need to explain this a lot better, you're probably looking for `concat()`, but who knows ? — adeneo, Dec 31 '13 at 11:36
see if [this](http://stackoverflow.com/questions/1187518/javascript-array-difference) helps you out — Manish Mishra, Dec 31 '13 at 11:37
@adeneo for SELECT with attribute multiple, jquery `val()` returns array. I was thinking the same... — A. Wolff, Dec 31 '13 at 11:39
@A.Wolff - It would, but plain javascript wouldn't, one of those convenient things added by jQuery. — adeneo, Dec 31 '13 at 11:43

KooiInc · Answer 1 · 2013-12-31T12:05:58.837

2

You can use Array.filter this way:

var c = [1,2,5]
          .filter(function(a){return this.indexOf(a) === -1},[1,2,4]); //=> [5]
var d = [1,2,4]
          .filter(function(a){return this.indexOf(a) === -1},[1,2,5]); //=> [4]

Or:

function notIn(a){
   return this.indexOf(a) === -1;
}
var a = [1,2,4]
   ,b = [1,2,5]
   ,c = b.filter(notIn,a)
   ,d = a.filter(notIn,b);

See also

edited Dec 31 '13 at 12:05

answered Dec 31 '13 at 11:44

KooiInc

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TypeError: a.filter is not a function.filter(function(a){return this.indexOf(a) === -1},[1,2,5]); //=> [4] – monda Dec 31 '13 at 12:06
@monda: in that case you probably need the shim/Polyfill from the 'See also' link. Idem for `indexOf`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf – KooiInc Dec 31 '13 at 12:07

score 1 · Answer 2 · answered Dec 31 '13 at 11:39

1

You can try the grep() method

var a1 = [1, 2, 4];
var a2 = [1, 2, 5];
var difference = $.grep(a1, function (x) {
                     return $.inArray(x, a2) < 0
                 });

alert(" the difference is " + difference);

JSFiddle

answered Dec 31 '13 at 11:39

chridam

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score 1 · Answer 3 · edited May 23 '17 at 12:28

1

I know this is an old question, but I thought I would share this little trick.

var diff = $(old_array).not(new_array).get();

diff now contains what was in old_array that is not in new_array

Found this on Compare 2 arrays which returns difference

edited May 23 '17 at 12:28

Community

1
1

answered Dec 31 '13 at 12:57

Nitin Varpe

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score 0 · Answer 4 · answered Dec 31 '13 at 11:41

try something like this

var a= [1,2,4];
var b= [1,2,5];

 var c = [];
 jQuery.each(b,function(k,v){
    if(a.indexOf(v) < 0){
        c.push(v);
    }
 })
 console.log(c);//[5]

 var d = [];
 jQuery.each(a,function(k,v){
    if(b.indexOf(v) < 0){
        d.push(v);
    }
 })
 console.log(d);//[4]

Javascript/Jquery- new array from existing two arrays

4 Answers4