//判断日期是否正确
String.prototype.isDate = function()
{
   var r = this.match(/^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2})$/); 
   if(r == null) return false;
   var d = new Date(r[1], r[3] - 1, r[4]); 
   return (d.getFullYear() == r[1] && (d.getMonth() + 1) == r[3] && d.getDate() == r[4]);
}

//去除字符串前后空格
String.prototype.trim = function()
{
    return this.replace(/(^\s*)|(\s*$)/g, "");
}

//判断是否为格式合法的邮箱
String.prototype.isEmail = function()
{
    // regEx = /^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/;
    var regEx = /^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/; 
    return regEx.test(this);
}