JavaScript实现页面加载时锁定表单元素

for(z=0;z<document.getElementsByTagName('input').length;z++)
{
 document.getElementsByTagName('input')[z].setAttribute('disabled','disabled')
}
for(zz=0;zz<document.getElementsByTagName('textarea').length;zz++)
{
 document.getElementsByTagName('textarea')[zz].setAttribute('readonly','readonly')
}
for(zzz=0;zzz<document.getElementsByTagName('select').length;zzz++)
{
 document.getElementsByTagName('select')[zzz].setAttribute('disabled','disabled')
}