fejl?

Hvad er fejlen i dette script...
den siger bare error on pages

<script language=\"JavaScript\">
function opret(thisform)
{
    var craptxt = \'Fejl:\\n\\n\';
    var crap = 1;
   
    if(thisform.password.value.length > \'20\')
    {
    craptxt = craptxt + \'Dit password må max være 20 cifre\\n\';
    crap = 1;
    }
    f(thisform.password.value.length < \'3\')
    {
    craptxt = craptxt + \'Dit password skal mindst være 4 cifre langt\\n\';
    crap = 1;
    }
    if(thisform.username.value.length > \'20\')
    {
    craptxt = craptxt +\'Dit password må max være 20 cifre\\n\';
    crap = 1;
    }
    if(thisform.username.value.length < \'4\')
    {
    craptxt = craptxt + \'Dit brugernavn skal mindst være 5 cifre langt\\n\';
    crap = 1;
    }

    if(crap ==1)
    {
    alert(craptxt);
    return false;
    }

}
</script>
<form action=\"lol.asp\" method=\"post\" onSubmit=\"return opret(this);\">
<input type=\"hidden\" name=\"action\" value=\"opret\">
Brugernavn : <input type=\"text\" name=\"username\" maxlength=\"20\"><br>
Password : <input type=\"text\" name=\"password\" maxlength=\"20\"><br>
Re-Type : <input type=\"text\" name=\"pwtjeck\" maxlength=\"20\"><br>
<input type=\"submit\" value=\"Opret\">
</form>