javascript - Merging JS array of objects -

ok have 2 objects want merge wondering best way is...

obj1 = [          {             id: 123,             list: [ {id:1}, {id:2}, {id: 3} ]          },          {            id: 456            list: [ {id:99}, {id:98}, {id: 97} ]          }        ]   obj1 = [          {             id: 123,             list: [ {id:1}, {id:4}, {id: 5} ]          },          {            id: 456            list: [ {id:99}, {id:100}, {id: 101} ]          }        ] 

i able call merge(obj1, obj2) , result like:

resultobj = [          {             id: 123,             list: [ {id:1}, {id:2}, {id:3}, {id:4}, {id: 5} ]          },          {            id: 456            list: [ {id:99}, {id:98}, {id:97}, {id:100}, {id: 101} ]          }        ] 

you can use foreach() group elements id on first level , 1 more foreach() , find() check objects in list , push array or assign existing object same id.

var obj1 = [{"id":123,"list":[{"id":1},{"id":2},{"id":3}]},{"id":456,"list":[{"id":99},{"id":98},{"id":97}]}]  var obj2 = [{"id":123,"list":[{"id":1},{"id":4},{"id":5}]},{"id":456,"list":[{"id":99},{"id":100},{"id":101}]}]             var result = []         var arr = [].concat(obj1, obj2)  arr.foreach(function(e) {    if(!this[e.id]) result.push(this[e.id] = e)    else {      var = this;      e.list.foreach(function(a) {        var o = that[e.id].list.find(c => a.id == c.id);        o ? object.assign(o, a) : that[e.id].list.push(a)      })    }  }, {})             console.log(result)