Let's say I have two objects.

obj1 = {
    a: 1,
    b: 3,
    c: 1
}

obj2 = {
    a: 3,
    b: 1,
    c: 3
}

And I would like to add these two. In a way that each key value add them together with the corresponding one. So obj3 = obj1 obj2 would result in:

obj3 = {
    a: 4,
    b: 4,
    c: 4
}

Is there a simpler way of doing this without manually adding each key value pair like

obj3.a = obj1.a   obj2.a

CodePudding user response：

This is something that could be done very simply through the use of Array.prototype.reduce() if you were able to store these objects as an array:

  const myObjects = [
    {
      a: 1,
      b: 3,
      c: 1,
    },
    {
      a: 3,
      b: 1,
      c: 3,
    },
  ];

  const output = myObjects.reduce((prev, curr) => ({
    a: prev.a   curr.a,
    b: prev.b   curr.b,
    c: prev.c   curr.c,
  }));

CodePudding user response：

This function sum property's object (dynamic property)

function objSumProperty(obj1, obj2) {
    const data = {};

    Object.keys(obj1).map((k) => (data[k] = obj1[k]   (obj2[k] || 0)));

  return data;
}

CodePudding user response：

Use parameters rest (...) to collect all objects to an array. Create an array of all entries ([key, value] pairs) using Array.flatMap() with Object.entries(). Reduce the array of entries to a single object.

This function allows you to combine all keys from 2 or more objects, even if the objects have different keys.

const fn = (...objs) => objs
  .flatMap(Object.entries)
  .reduce((acc, [key, value]) => ({
    ...acc, 
    [key]: (acc[key] ?? 0)   value
  }), {})
  

const obj1 = {"a":1,"b":3,"c":1}
const obj2 = {"a":3,"b":1,"c":3}

console.log(fn(obj1, obj2)) // combining 2 objects

const obj3 = {"a":10,"d":15,"e":20}

console.log(fn(obj1, obj2, obj3)) // combining 3 objects