js对象赋值，如何把原来的属性保留并修改，如果有新属性就追加新属性呢

Question

比如
let a = { 'name':'kelaier','age':'12'}
let b = {'name':'feifei','sex':'boy'}
把b赋值给a,保留a的属性age，修改name的属性，追加b的sex属性
前端小白不懂- -

Answer 1

a = {...a,...b};

Answer 2

Object.assign(a,b)

Object.assign

The Object.assign() method copies all enumerable own properties from one or more source objects to a target object. It returns the modified target object.