Remove multiple object from array of objects using filter

Question

Given,

someArray = [{name:"Kristian", lines:"2,5,10"},
             {name:"John", lines:"1,19,26,96"},
             {name:"Brian",lines:"3,9,62,36" }];

removeArray = [{name:"Kristian", lines:"2,5,10"},
             {name:"Brian",lines:"3,9,62,36" }];

How do I remove objects of removeArray from someArray? I can remove a single object:

johnRemoved = someArray.filter(function(el) {
return el.name !== "John";
});

However, instead of comparing someArray names to a string, I'd like to compare them to names in removeArray. Can it be done with a second filter method or does it have to be a for loop?

Jonas Wilms · Accepted Answer · 2017-11-03 23:02:34Z

4

You just need a second some iteration:

johnRemoved = someArray.filter( obj => !removeArray.some( obj2 => obj.name === obj2.name ));

answered Nov 3, 2017 at 23:02

Jonas Wilms

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Comments

trincot · Accepted Answer · 2017-11-03 23:00:38Z

2

You could use filter with the this object equal to the set of names that need removal (a Set for efficiency):

someArray = [{name:"Kristian", lines:"2,5,10"},
             {name:"John", lines:"1,19,26,96"},
             {name:"Brian",lines:"3,9,62,36" }];

removeArray = [{name:"Kristian", lines:"2,5,10"},
             {name:"Brian",lines:"3,9,62,36" }];
             
someArray = someArray.filter(function(obj) {
    return !this.has(obj.name);
}, new Set(removeArray.map(obj => obj.name)));

console.log(someArray);

answered Nov 3, 2017 at 23:00

trincot

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1 Comment

Jonas Wilms Over a year ago

Why not (set => obj => !set.has(obj))(new Set(..)) ?

PersyJack · Accepted Answer · 2017-11-04 02:23:55Z

I like the answers given here. I wanted to add my own as well.

1 - Two Array.prototype.filter() methods, first filter used for iteration:

removeArray.filter(function(ra) {
    someArray = someArray.filter(function(sa) {
        return sa.name !== ra.name;
    });
});

2 - first iteration can be replaced by for...of loop

for (let item of removeArray){

3- or by Array.prototype.forEach()

removeArray.forEach(function(ra) {

4- as dubbha, Adam and Jonas w mentioned, Array.prototype.some():

someArray.filter(i => !removeArray.some(j => j.name === i.name));

5- lastly trincot's answer was interesting for me:

someArray = someArray.filter(function(obj) {
  return !this.has(obj.name);
}, new Set(removeArray.map(obj => obj.name)));

Adam Jenkins · Accepted Answer · 2017-11-03 23:12:06Z

1

Filter and some:

someArray.filter(function(item) {
    return !removeArray.some(function(r) { return r.name == item.name && r.lines == item.lines })
});

answered Nov 3, 2017 at 23:12

Adam Jenkins

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Comments

dubbha · Accepted Answer · 2017-11-04 00:11:01Z

1

someArray.filter(i => !removeArray.map(j => j.name).includes(i.name));

or if you don't want to go beyond ES6 with includes:

someArray.filter(i => !removeArray.some(j => j.name === i.name));

or using reduce:

someArray.reduce((acc, i) => {
  !removeArray.some(j => j.name === i.name) && acc.push(i);
  return acc;
}, []);

edited Nov 4, 2017 at 0:11

answered Nov 3, 2017 at 23:09

dubbha

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Comments

Kacper Wiszczuk · Accepted Answer · 2017-11-03 23:03:42Z

0

That should do the trick.

const removed = someArray.filter((e) => {
    return removeArray.find(r => r.name === e.name) !== undefined;
});

answered Nov 3, 2017 at 23:03

Kacper Wiszczuk

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3 Comments

Walter Chapilliquen - wZVanG Over a year ago

why const?, and not var or let

Kacper Wiszczuk Over a year ago

You can use whatever you want. I am primarily using const because it prevents you from re-assigning new value to variable. Here you've got pretty nice article explaining the difference between those keywords.

Walter Chapilliquen - wZVanG Over a year ago

In this case to work with variables of our application we change them frequently, it is better to use var or` let. const more I would use it for configuration variables for example ...

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