function?count(){	
????var?sum?=?'';??//var?sum;?改成?var?sum?=?'';		
????var?first=?parseInt(document.getElementById("txt1").value);?//parseInt()?函數(shù)解析字符串，并返回一個(gè)整數(shù)	
????var?second=parseInt(document.getElementById("txt2").value);	
????var?select=document.getElementById("select").value;		
????switch(select)		
????{	?????	?????
????????case?'+':	?????????	?????
????????????sum?=?first?+?second;	?????????	?????
????????????break;?????????	?????
????????case?'-':????????????	?????
????????????sum?=?first?-?second;?????????????	?????
????????????break;?????????	?????
????????case?'*':????????????	?????
????????????sum?=?first?*?second;????????????	?????
????????????break;?????????	?????
????????case?'/':????????????	?????
????????????sum?=?first?/?second;????????????	?????
????????????break;		
????}	???	
????//return?sum;?	
????document.getElementById("fruit").value?=?sum;?//設(shè)置結(jié)果輸入框的值?
}