Js ?运算符(加减乘除)

var box=1+2 ??????????????????????//3var box=1+NaN ????????????????????//NaN,有一个为NaN就为NaNvar box=Infinity+Infinity 　　　　 //Infinityvar box=-Infinity + -Infinity ?　　//-Infinityvar box=Infinity + -Infinity ?　　 //NaN,正无穷和负无穷相加为NaNvar box=100+ ‘100‘; ???????　　　　//100100,有一个为字符串相加为字符串拼接var box=‘你的年龄是‘+10+20; ???　　 //你的年龄是1020,后面的整形已转换成字符串var box=‘你的年龄是‘+(10+20); 　　 ?//你的年龄是30,后面的整形先相加在转换吃字符串var box=10+20+‘是你的年龄‘; ??　　 ?//30是你的年龄,先相加,在转换成字符串var box=10+对象; ??????　　　　　　 //10[object Object],如果有toString()或valueOf()则返回10+返回的值

var box=1;box++; ????????//box=2,box=box+1++box; ????????//box=3,box=box+1var age=box++ ?//box=4;age=3,先赋值在运算var pox=++box ?//pox=5;box=5,先运算在赋值

var box=100-70; ?//30var box=-100-70; //-170var box=-100--70; //-30var box=-100-NaN ??//NaNvar box=Infinity-Infinity ??//NaNvar box=-Infinity--Infinity //NaNvar box=Infinity--Infinity //Infinityvar box=-Infinity-Infinity //-Infinityvar box=100-true; ????//99,true转换成数值为1var box=100-‘‘; ?????//100,‘‘转换为0

var box=100/70 ??///1.42....var box=100/NaN ??///NaNvar box=Infinity/Infinity ?///NaNvar box=-Infinity/Infinity ?///NaNvar box=-Infinity/-Infinity ?///NaNvar box=100/true ??????///100,true转换成1var box=100/‘‘ ?????????/// Infinityvar box=100/null ????????///Infinityvar box=100/‘lee‘ ????????///NaNvar box=100/对象 ???????????///NaN ,如果有toString()或valueOf(),返回10/返回值

var box=10%3; ????//1,余数为1var box=100%NaN; ?//NaNvar box=Infinity%Infinity ?//NaNvar box=100%true ???????//0var box=100%‘‘ ?????????//NaNvar box=100%null ???????//NaN