How to remove element from an array which as nested objects

Question

This is my array,

 arr = [
         {
           'User': {
              'id':1058,
              'name':'user67'
            },
            Source: {
               'dom':'pl-4'
            }
         },
         {
           'User': {
              'id':768,
              'name':'user13'
            },
            Source: {
               'dom':'pl-4'
            }
         }
       ];

I am using the following code to remove:

        arr= _.without(arr, _.findWhere(arr, {id: 768}));

I want to remove the user with id 768 but it somehow does not work.

How can I search in nested objects?

underscore methods dupe arrays, you need to use [].splice() to mutate. — dandavis
– dandavis, Commented Sep 10, 2014 at 19:00

Oriol · Accepted Answer · 2014-09-10 19:05:22Z

4

Using ES5 array methods,

arr = arr.filter(function(item) {
    return item.User.id !== 768;
});

Note it's short and clear, but a traditional for loop is faster.

answered Sep 10, 2014 at 19:05

Oriol

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3 Comments

dandavis Over a year ago

what for-loop code would run faster? my quick tests show filter() running about 24X faster in V8. for some reason, both jsPerf and jsFiddle run it slower, but if you run the code in jsfiddle.net/rndme/p64mpux3 in the devtools console here on stack, on google.com, or about:blank, then filter() is much faster. why it runs differently on the two sites that people use to test is beyond me...

Oriol Over a year ago

@dandavis ES5 array methods are usually slower because they run a function at each iteration, which is a bit slow; they create a new array instead of modifying the existing one; and they iterate all the array (assuming user id are unique, there is no need to keep iterating after finding the one to be removed).

dandavis Over a year ago

it's just that in some context, [].filter is WAY faster. also, for-in doesn't skip over sparse arrays, meaning it could do more work in some cases. you can sneak a closure into [].some() if you want to abort a functional iteration early, or use the newer [4,6,3,6,8].findIndex(Object.is.bind(null, 6))==1

Regent · Accepted Answer · 2014-09-10 19:03:49Z

2

You can still do it in plain JavaScript:

for (var i = 0; i < arr.length; i++)
{
    if (arr[i].User.id == 768)
    {
        arr.splice(i, 1);
        break;
    }
}

Fiddle.

answered Sep 10, 2014 at 19:03

Regent

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Comments

LcSalazar · Accepted Answer · 2014-09-10 19:06:31Z

1

Javascript has a nice Array method called map, that can map the properties of an object array. So you can splice the array's object on the selected index that contains a certain property, through this method:

arr.splice(
    arr.map(function(e) {
        return e["User"]["id"];
    }).indexOf(768)
    ,1
);

MDN Array.prototype.map() docs

Just note that it's IE compatibility starts from version 9.

answered Sep 10, 2014 at 19:06

LcSalazar

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Comments

Manish M Demblani · Accepted Answer · 2016-02-27 13:11:54Z

0

You can try the following

arr= _.reject(arr, function(obj) {
   return obj.User.id == 768;
});

answered Feb 27, 2016 at 13:11

Manish M Demblani

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