js-collect.js

function validateForm()  //必填项验证
{
  var x=document.forms["myForm"]["fname"].value;
  if (x==null || x=="")
  {
    alert("姓必须填写");
    return false;
  }
}
//实例
<form name="myForm" action="demo-form.php" onsubmit="return validateForm()" method="post">
姓: <input type="text" name="fname">
<input type="submit" value="提交">
</form>


function validateForm()//邮箱验证
{
  var x=document.forms["myForm"]["email"].value;
  var atpos=x.indexOf("@");
  var dotpos=x.lastIndexOf(".");
  if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length){
    alert("不是一个有效的 e-mail 地址");
    return false;
  }
}
//实例
<form name="myForm" action="demo-form.php" onsubmit="return validateForm();" method="post">
    Email: <input type="text" name="email">
    <input type="submit" value="提交">
</form>

function myFunction()//数字大小验证
{
    var x, text;

    // 获取 id="numb" 的值
    x = document.getElementById("numb").value;

    // 如果输入的值 x 不是数字或者小于 1 或者大于 10，则提示错误 Not a Number or less than one or greater than 10
    if (isNaN(x) || x < 1 || x > 10) {
        text = "输入错误";
    } else {
        text = "输入正确";
    }
    document.getElementById("demo").innerHTML = text;
}