Underscore JS difference on array and array with objects

Question

I'm having an array with certain numbers and an array with certain objects, looking like this:

var names = [
  { id: 1, name: 'Alex'},
  { id: 2, name: 'John'},
  { id: 3, name: 'Mary'}
];

var blocked_ids = [1, 2];

Now I would like to remove the objects with the blocked_ids from the names array. So the result would be this:

[
  { id: 3, name: 'Mary'}
]

As you can see the objects with id 1 and 2 are gone, because the array "blocked_ids" contained these numbers. If it where just two arrays, i could use _.difference(), but now I have to compare the blocked_ids with the id's inside the array's objects. Anyone knows how to do this?

Mritunjay · Accepted Answer · 2014-08-27 09:37:36Z

1

Assuming block-ids you have given is an array of Ids, You can use reject like bellow

var arr = [ { id: 1,
    name: 'Alex'},
  { id: 2,
    name: 'John'},
  { id: 3,
    name: 'Mary'}
];

var block_ids = [1,2];
var result = _.reject(arr, function (obj) {
    return block_ids.indexOf(obj.id) > -1;
}); 

console.log(result);

DEMO

answered Aug 27, 2014 at 9:37

Mritunjay

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1 Comment

Erik van de Ven Over a year ago

complete and clear answer. Thanks, works like a charm!

aymericbeaumet · Accepted Answer · 2014-08-27 09:42:12Z

0

You could do this by using the _.reject method.

For example:

_.reject(names, function(name) {
    return blockedIds.indexOf(name.id) > -1;
});

See this JSFiddle.

edited Aug 27, 2014 at 9:42

answered Aug 27, 2014 at 9:36

aymericbeaumet

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2 Comments

aymericbeaumet Over a year ago

Well I posted it first so... :) Anyway, glad it works. You could also consider @illfang's for a non-underscore solution.

Erik van de Ven Over a year ago

Ok you're right ;) Answers are almost identical and you were first, so I accepted your answer as the solution :P

illfang · Accepted Answer · 2014-08-27 09:48:52Z

0

Pure ECMAScript solution:

names.filter(function(element) {
    return blocked_ids.indexOf(element.id) === -1}
);

edited Aug 27, 2014 at 9:48

answered Aug 27, 2014 at 9:41

illfang

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