js 原色插到数组最后第二位

Question

怎么把b插入到a中，从a倒数第二个元素往后插入
a = [

{
    name:'1'
},
{
    name:'2'
},
{
    name:'3'
}

]

b = [

 {
    name:'4'
},
 {
    name:'5'
}

]

Answer 1

a.splice(-1, 0, ...b)
console.log(a)

Answer 2


a = [
{
    name:'1'
},
{
    name:'2'
},
{
    name:'3'
}
]

b = [
 {
    name:'4'
},
 {
    name:'5'
}
]
a.slice(0,-2).concat(b.concat(a.slice(-2)))
/*
0: {name: "1"}
1: {name: "4"}
2: {name: "5"}
3: {name: "2"}
4: {name: "3"}
length: 5
*/