Differences between JS valueof and toString

• valueOf Returns the object itself 、
• toString Returns the object description string

obj = new Object(); // {}
obj.toString(); // '[object Object]'
obj.valueOf() == obj // true

toString Is to convert an object into a string ;
valueOf Is to convert an object into a value of basic data

valueOf Biased towards arithmetic ,toString Tend to show .
1、 In object conversion （ for example :alert(a)）, Will call... First toString Method , If not rewritten toString Will call valueOf Method , If neither method is overridden , Press Object Of toString Output .
2、 When the string type is forcibly converted, the... Will be called first toString Method , When forced to a number, call... First valueOf.
3、 In the case of arithmetic operators ,valueOf Has a higher priority than toStri