split()字符串拆分--join('')字符串连接--reverse()颠倒数组中的元素

1、split('')  把一个字符串分割成数组
var str="How are you ?";
var n=str.split(" ");
输出结果：["How", "are", "you", "?"]

2、join('')   把数组中的所有元素连接为一个字符串
var fruits = ["Banana", "Orange", "Apple", "Mango"];
console.log(fruits.join());
输出结果：Banana,Orange,Apple,Mango

3、reverse()  颠倒数组中元素的顺序：
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.reverse();
输出结果：["Mango", "Apple", "Orange", "Banana"]