添加的是同一个对象的地址，所以无论改哪个数组内对象的值，另一个数组内对象的值也会被更改
a = [{name : '小红'}]
b1 = [ ...a ]
b2 = []
b2.push( a[0] )
// b1 = [{name : '小红'}]
// b2 = [{name : '小红'}]
a[0].name = '小兰’
// b1 = [{name : '小兰'}]
// b2 = [{name : '小兰'}]
b1[0].name = '小绿’
// a = [{name : '小绿'}]
// b2 = [{name : '小绿'}]
b2[0].name = '小五’
// a = [{name : '小五'}]
// b1 = [{name : '小五'}]