如何把js文件里的表单项写成变量?

Question

eval("document.form1."+city+".length=0;")

Answer 1

document.form1[city].length=0;document.getElementById(city).length=0;document.getElementsByName(city).length=0;

Answer 2

document.getElementById(city).length=0;
错误提示:document.getElementById(...)为空或不是对象eval("document.form1."+city+".length=0);
错误提示:缺少标识符

Answer 3

eval("document.form1."+city+".length=0");

Answer 4

function getObject(objName){
  var obj = document.getElementById(objName);
  if(obj.tagName=="SELECT"){
       return obj;
   }
  return null;
}这样一来可以得到一个SELECT对象把一个对象做为参数传递
function changecity(city){
    if(city.tagName == "SELECT"){
            document.form1.city.length=0;
     ...
   }
}还是传一个对象名比较好