function checkForm()
{

if(document.frm_postcode_input.postcode.value=="Your Postcode")
{
document.frm_postcode_input.postcode.value="";
document.frm_postcode_input.postcode.focus();
return false;
}

str = document.frm_postcode_input.postcode.value;
str = str.replace(/ /g,'');

if(str.length<5)
{
alert("Minimum postcode length is 5 characters.\nPlease try again.");
return false;
}

if(str.length>7)
{
alert("This is an invalid postcode.\nPlease try again.");
return false;
}

return true;
}