经常用到的js

<script>

var xmlHTTP=null;

var lastusername='';

function checkreturn(){

return (event.keyCode==13)?1:0;

}

function reg_check(){

if(document.getElementById('name').value.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) == -1)

{ alert('用户名格式输入错误!'); document.getElementById('name').focus();return;}

if(document.getElementById('password').value.length<6){

alert('您的密码长度小于6位,请重新输入!');document.getElementById('password').focus();return;

}

if(document.getElementById('password').value.length>20){

alert('您的密码长度大于20位,请重新输入!');document.getElementById('password').focus();return;

}

if(document.getElementById('name').value.length>32){

alert('您的用户名长度大于32位,请重新输入!');document.getElementById('name').focus();return;

}

if(document.getElementById('password').value!=document.getElementById('password1').value){

alert('您的填写的用户名密码与确认密码不一致，请重新输入!');document.getElementById('password').focus();return;

}if(document.getElementById('email').value == "")

{ alert('E-mail地址不能为空!'); document.getElementById('email').focus();return;}

if(document.getElementById('email').value.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) == -1)

{ alert('E-mail地址格式输入错误!'); document.getElementById('email').focus();return;}

document.forms['form1'].submit();

}

function clockon()

{

var now = new Date();

var year = now.getFullYear(); //getFullYear getYear

var month = now.getMonth();

var date = now.getDate();

var day = now.getDay();

var hour = now.getHours();

var minu = now.getMinutes();

var sec = now.getSeconds();

var week;

month = month+1;

if(month<10)month="0"+month;

if(date<10)date="0"+date;

if(hour<10)hour="0"+hour;

if(minu<10)minu="0"+minu;

if(sec<10)sec="0"+sec;

var arr_week = new Array("星期日","星期一","星期二","星期三","星期四","星期五","星期六");

week = arr_week[day];

var time = "";

time = year+"年"+month+"月"+date+"日"+" "+hour+":"+minu+":"+sec+" "+week;

document.getElementById("bgclock").innerHTML="["+time+"]";

var timer = setTimeout("clockon()",200);

}

function check_upper(){

var letter = document.getElementById('name').value;

if(letter.match("[A-Z]+"))

{

document.getElementById("checkname").innerHTML='<font color=red>用户名不能含大写英文字母!</font>';

}else{

document.getElementById("checkname").innerHTML='';

}

if(letter.match(/[\u4e00-\u9fa5]/g)){

document.getElementById("checkname").innerHTML='<font color=red>用户名不能含中文!</font>';

}

}

function _checkname()

{

if(xmlHTTP.readyState!=4)

return;

if(xmlHTTP.responseText == "ok"){

document.getElementById("checkname").innerHTML='<font color=green>该用户名可以使用!</font>';

}

else{

document.getElementById("checkname").innerHTML='<font color=red>该用户名已经存在，不可以使用!</font>';

}

}

function checkname(obj){

if (lastusername == obj.value)

{

return;

}

else

{

lastusername = obj.value;
}

if(lastusername.replace(/\s/g,"") == "")

{

document.getElementById("checkname").innerHTML='<font color=red>请输入用户名</font>';

obj.focus();

return;

}

if(lastusername.search(/^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/) == -1)

{

document.getElementById("checkname").innerHTML='<font color=red>用户名格式输入错误!</font>';

obj.focus();

return;

}

if(xmlHTTP==null){

xmlHTTP=new ActiveXObject("MSXML2.XMLHTTP");

}

xmlHTTP.abort();

xmlHTTP.onreadystatechange=_checkname;

xmlHTTP.open("GET","reg.php?act=checkname&checkname=" + encodeURI(lastusername),true);

xmlHTTP.send();

}

</script>