类型转换

JSON.stringify(obj)将JSON转为字符串。JSON.parse(string)将字符串转为JSON格式；

var a={"name":"tom","sex":"男","age":"24"}; 
var b='{"name":"Mike","sex":"女","age":"29"}'; 
var aToStr=JSON.stringify(a); 
var bToObj=JSON.parse(b); 
var queryOrder = jQuery.parseJSON(data);
alert(typeof(aToStr));  //string 
alert(typeof(bToObj));//object

数字，字符串互转

parseInt("1212blu");//1212
var a=1212;
a.toString()//"1212"

四舍五入保留小数点后几位

var n = 123456.789; 
n.toFixed(0); // "123457" 
n.toFixed(1); // "123456.8"