javastr=""; function Changepic() { document.getElementById("yzm").src="verif.asp?a=" + Math.random(); } function check_login(theForm) { if(theForm.username.value=="") { alert("请输入用户名"); theForm.username.focus(); return false; } if(theForm.password.value=="") { alert("请输入密码"); theForm.password.focus(); return false; } if(theForm.pic.value=="") { alert("请输入验证码"); theForm.pic.focus(); return false; } } javastr=javastr+"