1.数组转字符串
var a, b;
a = new Array(,,,,);
b = a.join("-");
2.字符串转数组
var s = "abc,abcd,aaa";
ss = s.split(",");
3.数字转字符串toString
var i = ;
var s = i.toString();
4.字符串转数字
parseInt(字符串)
parseInt("ssss999"); //错误
输出结果：NaN
parseInt("99ssss"); //正确
输出结果：99