How to create new JS array from an JS object

Question

I want to create new JS array from an object. I explained my scenario as below.

obj1

obj1 = {
  MMJ_KKL: {CODE: "SSW", YARN: 4500, WARN: "NBVC"},
  KKN_AAS: {CODE: "NNH", YARN: 1540, WARN: "MHYT"},
  LLK_PPO: {CODE: "KKI", YARN: 2312, WARN: "POIU"}
}

obj2

obj2 = {
  MMJ_KKL:{CODE: "SSW", YARN: 2300, WARN: "NBVC"},
  KKN_AAS:{CODE: "NNH", YARN: 3329, WARN: "MHYT"},
  LLK_PPO:{CODE: "KKI", YARN: 2312, WARN: "POIU"},
  RRE_WED:{CODE: "QQA", YARN: 4430, WARN: "IUYT"}
}

Now you all can see there is a change between obj1 and obj2. they are,

obj1.MMJ_KKL.YARN and obj2.MMJ_KKL.YARN
obj1.KKN_AAS.YARN and obj2.KKN_AAS.YARN Now it needs to create new array and put it the changed values.

******Note: we can not consider here RRE_WED in obj2. Because such value is not contained in obj1.

Tried code:

Object.keys(obj2).forEach((item) =>
    const result = obj1.filter((item) => arr1[item.code] && !(obj2[item.product_code].YARN === item.YARN && obj2[item.WARN].note === item.WARN));
);

Expected output:

[
  {
    "CODE": "SSW",
    "YARN": "2300",
    "WARN": "NBVC"
  },
  {
    "CODE": "NNH",
    "YARN": "3329",
    "WARN": "MHYT"
  }
]

Please help me to solve this problem.

@T.J.Crowder they are objects. I am complete new to JS. Please sorry for my terminology. — aer-der
– aer-der, Commented Nov 3, 2020 at 13:23
Your code loops through creating a new array every time (via filter) and then just throwing it away by not doing anything with it. You might want map rather than forEach, but it's hard to tell what you're doing here... — T.J. Crowder
– T.J. Crowder, Commented Nov 3, 2020 at 13:24
@T.J.Crowder I am doing here, compare obj1 and obj2. Then check YARN are similar or not. If there is a difference it should create new array as I mention in quection. — aer-der
– aer-der, Commented Nov 3, 2020 at 13:27

Edward Ellsworth · Accepted Answer · 2020-11-03 13:55:12Z

1

I'm not sure if I understand all the criteria you want to use, but this will give you the expected output.

Object.keys(obj1)
  .filter(key => Boolean(obj2[key]))
  .filter(key => obj1[key].YARN !== obj2[key].YARN)
  .map(key => obj2[key]);

answered Nov 3, 2020 at 13:55

Edward Ellsworth

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leLabrador · Accepted Answer · 2020-11-03 14:17:28Z

1

Assume that you want to merge obj2 to obj1:

1 - Use stringify to find attributes that have the changes.
2 - Use spread operator ... to merge obj2 to obj1.

Object.keys(obj1)
    .filter((k)=>JSON.stringify(obj1[k]) !== JSON.stringify(obj2[k]))
    .map((k)=> ({...obj1[k], ...obj2[k]}))

answered Nov 3, 2020 at 14:17

leLabrador

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