Username and Password Validation

<html>
<head>
<title>Username and Password Validation</title>
</head>
<body bgcolor=#ff9999>
<hr size=10 color=brown>
<font style="font-family:'Lucida Calligraphy'; font-size: 42px; background-color: #CCFF66;">
<marquee behavior=alternate scrollamount=5>Welcome</marquee>
</font>
<hr size=10 color=brown>
<h2>
<br>
<form name=test>
<font face="Segoe Print">
Enter Username :-</font>&nbsp;
<input type=text name=un style="height: 30px; width: 145px; font-size: 18px;">
<br><br>
<font face="Segoe Print">
Enter Password :-</font>&nbsp;&nbsp;
<input type=password name=pass style="width: 145px; height: 30px; font-size: 18px;">
</h2>
<br>
<p>
&nbsp;&nbsp;&nbsp;&nbsp;
<input type=button name=sub value="Submit" onClick=subform();
    style="width: 80px; height: 30px">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<input type=reset value="Reset" style="width: 80px; height: 30px">
</form>
<br>
<hr size=10 color=brown>
<marquee style="font-size: 41px; background-color:#CCFF66">
Site created by <u><b><i>Pramod</i></b></u>
</marquee>
<hr size=10 color=brown>
<h2 align=center>
&copy; 2014, IT education.
</h2>
<script language=javascript>
    function subform()
{
    if(nam() && ispass())
    {
    alert("VALID USERNAME AND PASSWORD")
    return true
    }
    else
    {
    return false
    }
}           
    function nam()
{
    var str
    str=document.test.un.value
    if(str=="")
    {
    alert("ENTER USERNAME")
    document.test.un.focus()
    return false
    }
    if(str!="" && str.length<7)
    {
    alert("USERNAME SHOULD BE MORE THAN 7 CHARACTERS")
    document.test.un.value=""
    document.test.un.focus()
    return false
    }
    for(var i=0;i<str.length-1;i++)
{
    var ch
    ch=str.charAt(i)
    if(((ch<'a'||'z'<ch)&&(ch<'A'||'Z'<ch)&&(ch!=' ' && ch!='-')))
    {
    alert("USERNAME ACCEPT ONLY LETTERS AND SPACE")
    document.test.un.focus()
    document.test.un.value=""
    return false
    }
    else
    {
    return true
    }
}
}                                             
    function ispass()
{
    var str1
    str1=document.test.pass.value
    if(str1=="")
    {
    alert("ENTER PASSWORD")
    document.test.pass.focus()
    return false
    }
    if(str1=="0000")
    {
    return true
    }
    else
    {
    alert("INVALID PASSWORD")
    document.test.pass.value=""
    document.test.pass.focus()
    return false
    }
}
</script>
</body>
</html>