javascript - 给定两个对象，如何将值从 obj2 复制到 obj1 而不覆盖 obj1 中的相似键？

Question

我有两个对象 obj1 和 obj2。我正在尝试将属性从 obj2 添加到 obj1，而不覆盖类似的属性

这是我到目前为止的代码:

var obj1 = {
  a: 1,
  b: 2
};
var obj2 = {
  b: 4,
  c: 3
};

function extend(objOne, objTwo) {
  objOne = Object.assign(objOne,objTwo)
  return objOne
}


extend(obj1, obj2)

console.log('obj1:', obj1)
console.log('obj2:', obj2)

Here's the result I'm having : 
// obj1: { a: 1, b: 4, c: 3 }
// obj2: { b: 4, c: 3 }

I'm almost there, but as you can see the `b` value in obj1 
is being overwritten by the `b`value from obj2  

my desired result would be :
// obj1: { a: 1, b: 2, c: 3 }
// obj2: { b: 4, c: 3 }

I tried using the spread operator but with no success

Answer 1

您可以使用空对象并切换 Object.assign 中对象的顺序.

然后使用新对象对 obj1 进行赋值。

var obj1 = { a: 1, b: 2 },
    obj2 = { b: 4, c: 3 };

Object.assign(obj1, Object.assign({}, obj2, obj1));
console.log(obj1); // { a: 1, b: 2, c: 3 }
console.log(obj2); // { b: 4, c: 3 }