Javascript - extract items from array based on id filter to create 2 arrays

Question

Im just looking for a good way to do this:

I have 2 arrays:

 var allItems = [
            {'id' : '1', 'title' : 'Title 1' },
            {'id' : '2', 'title' : 'Title 2' },
            {'id' : '3', 'title' : 'Title 3' },
            {'id' : '4', 'title' : 'Title 4' },
            {'id' : '5', 'title' : 'Title 5'},
            {'id' : '6', 'title' : 'Title 6' }
        ];

    var idsToExtract = ['1', '3', '6'];

I am looking for a result with two arrays that look like this:

    var array1 = [
            {'id' : '1', 'title' : 'Title 1' },
            {'id' : '3', 'title' : 'Title 3' },
            {'id' : '6', 'title' : 'Title 6'}
        ];

    var array2 = [
            {'id' : '2', 'title' : 'Title 2' },
            {'id' : '4', 'title' : 'Title 4' },
            {'id' : '5', 'title' : 'Title 5'}
        ];

I am ONLY using native JS ( ES2015 ) array methods.( map/filter etc).

NO jquery/underscore etc.

Thanks!

Dmitri Pavlutin · Accepted Answer · 2016-03-04 06:50:26Z

The Array.prototype.filter() method can help you:

var allItems = [
            {'id' : '1', 'title' : 'Title 1' },
            {'id' : '2', 'title' : 'Title 2' },
            {'id' : '3', 'title' : 'Title 3' },
            {'id' : '4', 'title' : 'Title 4' },
            {'id' : '5', 'title' : 'Title 5'},
            {'id' : '6', 'title' : 'Title 6' }
        ];

var idsToExtract = ['1', '3', '6'];

var array1 = allItems.filter(function(item) {
  return idsToExtract.indexOf(item.id) !== -1;
});

var array2 = allItems.filter(function(item) {
  return idsToExtract.indexOf(item.id) === -1;
});

Of course you can use Array.prototype.foreach() method, and create the 2 arrays in one iteration cycle:

var allItems = [
            {'id' : '1', 'title' : 'Title 1' },
            {'id' : '2', 'title' : 'Title 2' },
            {'id' : '3', 'title' : 'Title 3' },
            {'id' : '4', 'title' : 'Title 4' },
            {'id' : '5', 'title' : 'Title 5'},
            {'id' : '6', 'title' : 'Title 6' }
        ];

var idsToExtract = ['1', '3', '6'],
  array1 = [],
  array2 = [];

allItems.forEach(function(item) {
  idsToExtract.indexOf(item.id) !== -1 ? array1.push(item) : array2.push(item);
});

Cymen · Accepted Answer · 2016-03-04 07:02:46Z

1

Use Array.prototype.filter():

var array1 = allItems.filter((x) => idsToExtract.includes(x.id));
var array2 = allItems.filter((x) => !idsToExtract.includes(x.id));

JSFiddle: https://jsfiddle.net/ykcdvp9v/1/

edited Mar 4, 2016 at 7:02

answered Mar 4, 2016 at 6:42

Cymen

14.5k4 gold badges58 silver badges77 bronze badges

2 Comments

Cymen Over a year ago

@29er yeah, ES6 really makes the one liners clean and fun!

Amit Over a year ago

ES2015 has includes(). Use it...

Harshal · Accepted Answer · 2016-03-04 07:15:23Z

0

Using simple for loop

var allItems = [
            {'id' : '1', 'title' : 'Title 1' },
            {'id' : '2', 'title' : 'Title 2' },
            {'id' : '3', 'title' : 'Title 3' },
            {'id' : '4', 'title' : 'Title 4' },
            {'id' : '5', 'title' : 'Title 5'},
            {'id' : '6', 'title' : 'Title 6' }
        ];

var idsToExtract = ['1', '3', '6'],

    var remainingItemsArray= [];
    var extractedItemsArray= [];
    for(var i=0;i<allItems.length;i++){
            var item = allItems[i];
            if(idsToExtract.indexOf(item.id) != -1){
                remainingItemsArray.push(item);
            }else{
                extractedItemsArray.push(item);
            }        
    }

answered Mar 4, 2016 at 7:15

Harshal

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