1、What
splice()方法 可以删除、添加新元素来修改数组。
返回值：由被删除元素组成的数组。如果没有删除元素，则返回空数组。
2、How
⑴语法
array.splice(start)
array.splice(start, deleteCount)
array.splice(start, deleteCount, item1, item2, ...)
参数说明：
start 指定修改开始位置。（从0计数）
deleteCount 可选。整数，表示要移除元素个数
item1, item2, ... 可选。要添加元素，从start位置开始
⑵实例
例1：
var myFish = ["angel", "clown", "mandarin", "surgeon"];
//从第 2 位开始删除 0 个元素，插入 "drum"
var removed = myFish.splice(2, 0, "drum");
//运算后的 myFish:["angel", "clown", "drum", "mandarin", "surgeon"]
//被删除元素数组：[]，没有元素被删除
//从第 3 位开始删除 1 个元素
removed = myFish.splice(3, 1);
//运算后的myFish：["angel", "clown", "drum", "surgeon"]
//被删除元素数组：["mandarin"]
//从第 2 位开始删除 1 个元素，然后插入 "trumpet"
removed = myFish.splice(2, 1, "trumpet");
//运算后的myFish: ["angel", "clown", "trumpet", "surgeon"]
//被删除元素数组：["drum"]
//从第 0 位开始删除 2 个元素，然后插入 "parrot", "anemone" 和 "blue"
removed = myFish.splice(0, 2, "parrot", "anemone", "blue");
//运算后的myFish：["parrot", "anemone", "blue", "trumpet", "surgeon"]
//被删除元素的数组：["angel", "clown"]
//从第 3 位开始删除 2 个元素
removed = myFish.splice(3, Number.MAX_VALUE);
//运算后的myFish: ["parrot", "anemone", "blue"]
//被删除元素的数组：["trumpet", "surgeon"]```
例2：http://www.jianshu.com/p/8188d9f51978