E-mail验证判断代码！

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your email:

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{以下为关键代码，详细看演示}

mail.html内容

电子邮箱： 

validate.js内容

function checkemail(name, data, allowednull)
{
  var datastr = data;
  var lefttrim = datastr.search(/S/gi);
 
  if (lefttrim == -1) {
    if (allowednull) {
      return 1;
    } else {
      alert("请输入一个正确的E-mail地址！");
      return -1;
    }
  }
  var myRegExp = /[a-z0-9](([a-z0-9]|[_-.][a-z0-9])*)@([a-z0-9]([a-z0-9]|[_-][a-z0-9])*)((.[a-z0-9]([a-z0-9]|[_-][a-z0-9])*)*)..([a-z0-9]([a-z0-9]|[_-][a-z0-9])*)((.[a-z0-9]([a-z0-9]|[_-][a-z0-9])*)*)/gi;
  var answerind = datastr.search(myRegExp);
  var answerarr = datastr.match(myRegExp);
 
  if (answerind == 0 && answerarr[0].length == datastr.length)
  {
    return 0;
  }
 
  alert("请输入一个正确的E-mail地址！");
  return -1;
}
function parseNum(theNum){
  if (theNum.substring(0,1)==0)
    theNum=theNum.substring(1)
  return theNum
}