How to compare two arrays of objects to find the differences

Lincoln347

Actually, I meet with an iterate problem when I compare two arrays of objects.

Array Old:

[{uuid:'a'}, {uuid:'b'}, {uuid:'c'}]

Array New:

[{uuid:'a'}, {uuid:'e'}, {uuid:'f'}]

what I am going to do is calling the api under the below logic:

compare 'new' with 'old' to get the result:

[{name:1, uuid:'e'}, {name:1, uuid:'f'}]

and then call the POST api one by one to add new uuid: 'e' and 'f'

compare 'new' with 'old' to get the result:

[{name:1, uuid:'b'},{name:1, uuid:'c'}]

and then call the Delete api one by one to delete uuid: 'b' and 'c'

I have tried the below code to find the difference, but it seems not correct:(need some help)

  const postArr = [];
  for (var i = 0; i < this.new.length; i++) {
    for (var o = 0; o < this.old.length; o++) {
      if (
        this.new[i].uuid !==
        this.old[o].uuid
      ) {
        postArr.push(this.new[i]);
      }
    }
  }
  console.log(postArr);

pc_coder

with filter and mapping u can achive uniques in old array

var a=[{uuid:'a'}, {uuid:'b'}, {uuid:'c'}];
 var b=[{uuid:'a'}, {uuid:'e'}, {uuid:'f'}];
 var keys = ['uuid'];
 
 console.log(findDifferences(a,b))



function findDifferences(objectA, objectB) {
 
  var result = objectA.filter(function(o1){
    return !objectB.some(function(o2){
        return o1.uuid === o2.uuid;       
    });
  }).map(function(o){

      return keys.reduce(function(newo, name){
          newo[name] = o[name];
          return newo;
      }, {});
  });
  return result;
}

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