这得看你想要哪些判断条件,如果就单纯判断不为空:
<script language ="javascript">
function OK()
{
var aa = document.getElementById("text1").value;
if(aa.length=="")
{
alert("必须填写");
return false;
}
else
{
return ture;
}
}</script>
<input type="text" id="text1">
<input type="button" id="button1" value="提交" onclick="OK()">
<script language ="javascript">
function OK()
{
var aa = document.getElementById("text1").value;
if(aa.length=="")
{
alert("必须填写");
return false;
}
else
{
return ture;
}
}</script>
<input type="text" id="text1">
<input type="button" id="button1" value="提交" onclick="OK()">
function OK()
{
var aa = document.getElementById("text1").value;
if(aa.length<1)
{
alert("必须填写");
return false;
}
else
{
return ture;
}
}</script>
<input type="text" id="text1">
<input type="button" id="button1" value="提交" onclick="OK()">
{
ClientScript.RegisterStartupScript(this.GetType(), "", "<script>alert('密码不能为空!')</script>");
this.txt_userPwd.Focus();//获取焦点
return;
}
else
{
}
{}return checkform();
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>新建网页 1</title>
</head><body>
<form action="123.htm" method="get">
<input>
<input type="submit" value="submit" onclick="return checkNull();">
<input name="T1" size="20"><input name="T2" size="20"><input name="T3" size="20"><input name="T4" size="20"></form>
<script>
function checkNull()
{
var inputs = document.getElementsByTagName("INPUT");
for(var i = 0 ; i < inputs.length;i++)
{
if(inputs[i].type==null || (inputs[i].type!=null&&inputs[i].type.toLowerCase()=="text"))
{
if(inputs[i].value.replace(/ /g,"")=="")
{
alert("请填写所有的内容");
return false;
}
}
}
}
</script>
</body></html>