function change(arrayList,index,...value){
arrayList.splice(index,0,...value);
return arrayList;
}
let arr=[1,2,3,4,5]
console.log(change(arr,0,'z','2'));
//['z', '2', 1, 2, 3, 4, 5]
arr=[1,2,3,4,5];
console.log(change(arr,3,'z','2'));
//[1, 2, 3, 'z', '2', 4, 5]
arr=[1,2,3,4,5];
console.log(change(arr,6,'z','2'));
//[1, 2, 3, 4, 5, 'z', '2']
arr=[1,2,3,4,5];
console.log(change(arr,100,'z','2'));
//[1, 2, 3, 4, 5, 'z', '2']
//超过长度不会按下标位置填入
arr.splice(开始下标,删除位数,插入值)