function keyPair(obj1, obj2, key) {
if(key in obj1) return obj1[key];
if(key in obj2) return obj2[key];
return null;
}
let obj1 = {name: "Tom", age: 18};
let obj2 = {name: "Jerry", gender: "male"};
let key = "name";
let result = keyPair(obj1, obj2, key);
console.log(result); // 输出 "Tom"
解决方法解释: