var form = document.getElementById("dateform");
var a = form.elements.length;//Number of all controls
for (var j=0;j
if (form.elements[j].className == "text"){//Control with class="text"
if(form.elements[j].value=="" || form.elements[j] .value==null){
alert("cannot be null");
form.elements[j].focus();
return false;
}
}
}
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
