js向数组指定下标插入数据

例如 var list = [{id:0, name: ‘zhangSan’},{id:1, name: ‘lisi’}]
向list下标0插入对象

var item={id:2, name: 'wangwu'},
this.list.splice(0,1,item)
// 结果是 [{id:2, name: 'wangwu'} ，{id:0, name: 'zhangSan'},{id:1, name: 'lisi'}]