javascript 遍历验证所有文本框的值

var aa = document.getElementsByTagName("input"); 
var bb = 0; 
for(var i=0;i<aa.length;i++) 
{ 
var avalue = aa[i].value; 
var atype = aa[i].type; 
if(atype == "text") 
bb++; 
} 
alert("共有"+bb+"项text")