Underscore array operations for array of objects

Question

Underscore provides handy function for array intersection, difference and union. But they don't work as expected for array of objects:

var first = {val: 1};
var otherFirst = {val: 1};
var second = {val: 2};
_.difference([first, second], [otherFirst]); // result is [first, second] instead of [second]

This happens because JS checks objects for reference equality. How can I intersect two arrays of objects?

I'm looking for some kind of idiomatic solution.

Mritunjay · Accepted Answer · 2014-07-18 12:18:58Z

2

I've got something which will work for two arrays.

_.filter([first,second], function(obj){
    return !_.findWhere([otherFirst], obj); 
});

Basically what it's dong it's checking if an object in the array1 is not present in array2 filter that.

answered Jul 18, 2014 at 12:18

Mritunjay

25.9k7 gold badges57 silver badges71 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Bergi · Accepted Answer · 2014-07-18 13:54:44Z

0

Using remove will work:

_.remove([first, second], otherFirst)

answered Jul 18, 2014 at 13:54

Bergi

671k162 gold badges1k silver badges1.5k bronze badges

2 Comments

kharandziuk Over a year ago

Does it work when there are more than one element in second array?

Bergi Over a year ago

No, that would need an explicit callback. And I just noticed that underscore actually doesn't even have a remove method, it is lodash-specific.

Collectives™ on Stack Overflow

Underscore array operations for array of objects

2 Answers 2

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related