check the difference between two arrays of objects in javascript [duplicate]

Question

I need some help. How can I get the array of the difference on this scenario:

var b1 = [
  { id: 0, name: 'john' }, 
  { id: 1, name: 'mary' }, 
  { id: 2, name: 'pablo' }, 
  { id: 3, name: 'escobar' } 
]; 

var b2 = [
  { id: 0, name: 'john' }, 
  { id: 1, name: 'mary' }
];

I want the array of difference:

// [{ id: 2, name: 'pablo' }, { id: 3, name: 'escobar' }]

How is the most optimized approach?

I´m trying to filter a reduced array.. something on this line:

var Bfiltered = b1.filter(function (x) {
return x.name !== b2.reduce(function (acc, document, index) {
    return (document.name === x.name) ? document.name : false
},0)

});

console.log("Bfiltered", Bfiltered);
// returns { id: 0, name: 'john' }, { id: 2, name: 'pablo' }, { id: 3, name: 'escobar' } ]

Thanks,

Robot

Answer 1

.Filter() and .some() functions will do the trick

var b1 = [
  { id: 0, name: 'john' }, 
  { id: 1, name: 'mary' }, 
  { id: 2, name: 'pablo' }, 
  { id: 3, name: 'escobar' } 
]; 

var b2 = [
  { id: 0, name: 'john' }, 
  { id: 1, name: 'mary' }
];

var res = b1.filter(item1 => 
!b2.some(item2 => (item2.id === item1.id && item2.name === item1.name)))

console.log(res);

Answer 2

You can use filter to filter/loop thru the array and some to check if id exist on array 2

var b1 = [{ id: 0, name: 'john' }, { id: 1, name: 'mary' }, { id: 2, name: 'pablo' }, { id: 3, name: 'escobar' } ]; 
var b2 = [{ id: 0, name: 'john' }, { id: 1, name: 'mary' }];

var result = b1.filter(o => !b2.some(v => v.id === o.id));

console.log(result);

---

Above example will work if array 1 is longer. If you dont know which one is longer you can use sort to arrange the array and use reduce and filter.

var b1 = [{ id: 0, name: 'john' }, { id: 1, name: 'mary' }, { id: 2, name: 'pablo' }, { id: 3, name: 'escobar' } ]; 
var b2 = [{ id: 0, name: 'john' }, { id: 1, name: 'mary' }];

var result = [b1, b2].sort((a,b)=> b.length - a.length)
                     .reduce((a,b)=>a.filter(o => !b.some(v => v.id === o.id)));

console.log(result);