关于定义变量的问题，然后赋值求和，出现了问题，求解释？

Question

var mynum,mymun,sum;
mynum="8"; mymun="7"; 
sum=mynum+mymun;
document.write(sum);

为啥输出的结果是87，不是15

Answer 1

About the problem of defining variables, then assigning values ​​and summing, a problem occurs, please explain? -PHP Chinese website Q&A-About the problem of defining variables, then assigning values ​​and summing, a problem occurs, please explain? -PHP Chinese website Q&A

Please watch and learn.

Answer 2

问题出在你定义mynum="8"; mymun="7"; 

也就是说你将mynum定义为字符“8”，而非数字8，这两者是有完全不同的。mynun同理。

解决方法：mynum = 8 ; mymun = 7 ;