检查Object1的键是否在Object2中，如果比较

Question

How would I go about doing the following. I need to see if my object1.keys are in object2, if the key is there I need to compare the value, if the values are different I need to replace Object2's value with Object1's value.

Object1:

object1 = {
   firstName: "Bob",
   lastName: "Smith",
   dob: "May 25, 1977"
}

Object2:

object2 = {
   firstName: "Bobby",
   lastName: "Jones",
   dob: "May 25, 1977",
   created: "May 24, 1977",
   userLevel: "jedi"
}

Desired output for Object2:

object2 = {
   firstName: "Bob",
   lastName: "Smith",
   dob: "May 25, 1977",
   created: "May 24, 1977",
   userLevel: "jedi"
}

Answer 1

 Object.assign(object2, object1);

or to not mutate object2 but creating a new object:

 const newObj = {...object2, ...object1}

That assigns all values from object1 to object2. If they are the same, it doesnt matter if we copy them.

Answer 2

Just use for in on first object and compare

 let object1 = { firstName: "Bob", lastName: "Smith", dob: "May 25, 1977" } let object2 = { firstName: "Bobby", lastName: "Jones", dob: "May 25, 1977", created: "May 24, 1977", userLevel: "jedi" } for(let key in object1){ if(object2[key]){ object2[key] = object1[key] } } console.log(object2);