Merge two objects which have same keys and convert values to array

Question

var obj1 = {name: “John”, hobby: “Football”}

var obj2 = {hobby: “Basketball”}

These are my two object. I want to merge them and my result will be

   var obj1 = {name: “John”, hobby :[“Foootbal”,”Basketball”]}

How can ı do this ?

Does this answer your question? [Merge javascript objects in array with same key](https://stackoverflow.com/questions/33850412/merge-javascript-objects-in-array-with-same-key) — Zac Anger, Jan 15 '21 at 19:12
This doesn't looks like a merge. We could consider a merge if both `obj1` and `obj2` are strictly the type. In this case, you could **reduce** it in a new type — Jan Cássio, Jan 15 '21 at 19:13

ecoplaneteer · Answer 1 · 2021-01-15T19:56:52.777

4

var obj1 = {name: "John", hobby: "Football"}

var obj2 = {hobby: "Basketball"}
var obj3 = {hobby: "Tennis"}

const merge = (obj1, obj2) => {
    Object.keys(obj1).forEach(key => { if (obj2[key]) obj1[key] = [...[obj1[key]], obj2[key]].flat() })
}

merge(obj1, obj2)
merge(obj1, obj3)

console.log(obj1)

edited Jan 15 '21 at 19:56

answered Jan 15 '21 at 19:21

ecoplaneteer

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Thank you so much.. How can ı do dymanic this code ? I want to add some values in hobby dynamic ? – Mustafa Uysal Jan 15 '21 at 19:46
Put the operative line in a function. But it cannot reprocess data, it assumes you have only comparable strings as values. So if you re-ran the merge, you would get an array in an array. – Trevor Jan 15 '21 at 19:50
1

Update code to dynamically merge objects – ecoplaneteer Jan 15 '21 at 19:57

score 0 · Answer 2 · answered Jan 15 '21 at 19:35

const obj1 = {name: "John", hobby: "Football"}

const obj2 = {hobby: "Basketball"}

const obj3 = {}
for (const key in obj1){
  if (obj2[key] === undefined){
    obj3[key] = obj1[key]    
  }else{    
    obj3[key] = [ obj1[key], obj2[key] ]
  }
}
console.log(obj3)

Slightly different solution. Does not alter original objects.

Merge two objects which have same keys and convert values to array

2 Answers2