var now = Number(year) + Number(number)
把 year转成数字 输入的也转成数字
最简单的就是*1 ,会自动转换成数字
year*1 +num*1 //例如 let a ='200' let b='15' console.log(a*1 + b*1) //输出215
var now = (year-0)+ (number-0)