复制Javascript对象属性

const obj1 = { a: 1, b: 2 };
const obj2 = { c: 3, d: 4 };
const obj3 = Object.assign({}, obj1, obj2);
console.log(obj3); // { a: 1, b: 2, c: 3, d: 4 }

const obj1 = { a: 1, b: 2 };
const obj2 = { c: 3, d: 4 };
const obj3 = { ...obj1, ...obj2 };
console.log(obj3); // { a: 1, b: 2, c: 3, d: 4 }

const obj1 = { a: 1, b: 2 };
const obj2 = { c: 3, d: 4 };
const obj3 = {};
for (let key in obj1) {
  obj3[key] = obj1[key];
}
for (let key in obj2) {
  obj3[key] = obj2[key];
}
console.log(obj3); // { a: 1, b: 2, c: 3, d: 4 }

const obj1 = { a: 1, b: 2 };
const obj2 = { c: 3, d: 4 };
const obj3 = Object.keys(obj1).reduce((acc, key) => {
  acc[key] = obj1[key];
  return acc;
}, {});
Object.keys(obj2).reduce((acc, key) => {
  acc[key] = obj2[key];
  return acc;
}, obj3);
console.log(obj3); // { a: 1, b: 2, c: 3, d: 4 }