使用underscore.js从数组中删除多个项目？

Question

I have this:

var arrA = [{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}];

I have another array:

var arrB = [{id:1,other:'c'},{id:3,other:'d'}];

How can I remove the items from arrA that have property id same as arrB using underscore.js?

The expected result should be:

arrA = [{id:2, name:'b'}];

Thanks,

Answer 1

Using Array#filter and Array#findIndex

var output = arrA.filter((el) => {
  return arrB.findIndex((elem) => {
    return elem.id == el.id;
  }) == -1;
});

One liner:

arrA.filter((el) => (arrB.findIndex((elem) => (elem.id == el.id)) == -1));

---

 var arrA = [{ id: 1, name: 'a' }, { id: 2, name: 'b' }, { id: 3, name: 'c' }]; var arrB = [{ id: 1, other: 'c' }, { id: 3, other: 'd' }]; var op = arrA.filter(function(el) { return arrB.findIndex(function(elem) { return elem.id == el.id; }) == -1; }); console.log(op); 

Or using Array#find

 var arrA = [{ id: 1, name: 'a' }, { id: 2, name: 'b' }, { id: 3, name: 'c' }]; var arrB = [{ id: 1, other: 'c' }, { id: 3, other: 'd' }]; var op = arrA.filter(function(el) { return !arrB.find(function(elem) { return elem.id == el.id; }); }); console.log(op); 

Answer 2

Like this

var arrA = [{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}];
var arrB = [{id:1,other:'c'},{id:3,other:'d'}];
var keys = _.keys(_.indexBy(arrB, "id"));
var result = _.filter(arrA, function(v) {
   return !_.contains(keys, v.id.toString());
});
console.log(result)

Hope this helps.

Answer 3

In pure javascript you can use forEach() loop and splice() to remove object if it's id is found in other array.

 var arrA = [{id:1,name:'a'},{id:2,name:'b'},{id:3,name:'c'}]; var arrB = [{id:1,other:'c'},{id:3,other:'d'}]; var b = arrB.map(e => e.id); arrA.forEach(function(e, i) { if(b.indexOf(e.id) != -1) arrA.splice(i, 1); }); console.log(arrA); 

Answer 4

Sounds like you want the difference, but unfortunately that won't work for objects. Instead you could try this:

arrA = _.filter(arrA, function(obj){
           return !_.findWhere(arrB, {id: obj.id});
       });

You could do this without underscore using the build in filter and find functions.

Answer 5

 var arrA = [{id:1,name:'a'}, {id:2,name:'b'}, {id:3,name:'c'}]; var arrB = [{id:1,other:'c'}, {id:3,other:'d'}]; var res = arrB.reduce((acc, b) => { return acc.filter(({id}) => id !== b.id); }, arrA); // [{id:2,name:'b'}] console.log(res);