//自定义trim()函数
String.prototype.trim= function(){  
    // 用正则表达式将前后空格  
    // 用空字符串替代。  
    return this.replace(/(^\s*)|(\s*$)/g, "");  
}    
    

    function show(ele)
    {
      eval(ele + ".style.display = ''");
    }
    function hidden(ele)
    {
      eval(ele + ".style.display = 'none'");
    }
    
  var loginSet = document.getElementById("loginSet");
  var mbDIV = document.getElementById("mbDIV");
  var loginDIV = document.getElementById("loginDIV");
  var loginTopDIV = document.getElementById("loginTopDIV");

  document.getElementById("button_1").onclick = function() {
                                                  
  var loginForm = document.getElementById("loginForm");
  var userName = document.getElementById("username");
  var password = document.getElementById("password");
  var checkcode  = document.getElementById("checkcode");
      
   if(userName.value.trim() ==""){
        alert("对不起,用户名不能为空!");
        return false;
    }
      
    if(password.value.trim() ==""){
        alert("对不起,密码不能为空!");
        return false;
    }
    if(checkcode.value.trim() ==""){
        alert("请输入验证码!");
        return false;
    }  
 
    loginForm.submit();  
    hidden("loginDIV");
    //hidden("mbDIV"); 
 }
    
    
  document.getElementById("button_2").onclick = function()
                                                {
                                                  hidden("loginDIV");
                                                  hidden("mbDIV");
                                                }
  loginSet.onclick = function()
                 {
                   loginDIV.style.top = "200px";
                   loginDIV.style.left = document.body.scrollWidth/2-175;
                   mbDIV.style.height = document.body.scrollHeight;
                   show("loginDIV");
                   show("mbDIV")
                 }

/**
*这里写的是拖动信息
* */
    loginTopDIV.onmousedown = Down;
    var tHeight,lWidth;
    function Down(e)
    {
        var event = window.event || e;
        tHeight = event.clientY  - parseInt(loginDIV.style.top.replace(/px/,""));
        lWidth  = event.clientX - parseInt(loginDIV.style.left.replace(/px/,""));
        document.onmousemove = Move;
        document.onmouseup   = Up;
    }
    function Move(e) {
        var event = window.event || e;
        var top = event.clientY - tHeight;
        var left = event.clientX - lWidth;
        //判断 top 和 left 是否超出边界
        top = top < 0 ? 0 : top;
        top = top > document.body.offsetHeight - 150 ? document.body.offsetHeight - 150 : top;
        left = left < 0 ? 0 : left;
        left = left > document.body.offsetWidth - 380 ? document.body.offsetWidth - 380 : left;
        loginDIV.style.top  = top + "px";
        loginDIV.style.left = left +"px";
    }
    function Up() {
        document.onmousemove = null;
    }