function app2(x,y)

Question

   function  app2(x,y)  {         sum = x * y;    //return sum;   // alert(sum)  } var moust = app2(2,8)document.write(moust);怎么document.write(moust);这一句中要用变量名称，，二不用sum

Answer 1

 function  app2(x,y)
  {   
    sum = x * y;
    //return sum;
   // alert(sum)
  }
 var moust = app2(2,8)

document.write(moust);

这段代码运行后是undefined，如果想正常显示需要return sum;因为在return sum后,调用app2这个方法会返回sum值赋值给moust、