数组splice()方法

//splice()方法，向数组中插入项，插入方式有3种

//1、删除----可以删除任意数量的项，只需指定2个参数：要删除的第一项的位置和要删除的项数
var colors = ["red", "green", "yellow", "black", "brown"];
var removed = colors.splice(1,3);

console.log(removed);//["green", "yellow", "black"] 从第1个位置开始，删除3个
console.log(colors);//["red", "brown"]

//2、插入----可以向指定位置插入任意数量的项，只需提供3个参数：起始位置、0(要删除的项数)、要插入的项(如果要插入多个项，可以再传入第4，第5以至任意多个项)。
var colors2 = ["red", "green", "yellow", "black", "brown"];
colors2.splice(2, 0, "orange", "blue");

console.log(colors2);//["red", "green", "orange", "blue", "yellow", "black", "brown"]    从第2个位置插入orange, blue

//3、替换--原理和插入差不过，插入把第2个参数设置为0，替换则把0改为你想要替换的项目个数就行了
var colors3 = ["red", "green", "yellow", "black", "brown"];
var removed3 = colors2.splice(2, 3, "orange", "blue");

console.log(removed3);//["yellow", "black", "brown"]    从第2个位置开始删除3个
console.log(colors3);//["red", "green", "orange", "blue"]    从第2个位置删除3个，并插入orange, blue