添加的是同一個對象的地址，所以無論改哪個數組內對象的值，另一個數組內對象的值也會被更改
a = [{name : '小紅'}]
b1 = [ ...a ]
b2 = []
b2.push( a[0] )
// b1 = [{name : '小紅'}]
// b2 = [{name : '小紅'}]
a[0].name = '小蘭’
// b1 = [{name : '小蘭'}]
// b2 = [{name : '小蘭'}]
b1[0].name = '小綠’
// a = [{name : '小綠'}]
// b2 = [{name : '小綠'}]
b2[0].name = '小五’
// a = [{name : '小五'}]
// b1 = [{name : '小五'}]