function trim(str)
{
   return str.replace(/^\s+|\s+$/g,'');
}

function validatemail(str) 
{
   if(str.match(/^[a-zA-Z]+([_\.-]?[a-zA-Z0-9]+)*@[a-zA-Z0-9]+([\.-]?[a-zA-Z0-9]+)*(\.[a-zA-Z]{2,4})+$/) ==null)
   {
		return false;
   }
   else
   {
		return true;
   }
}


function checkform(arrreqfields,arrreqfieldsdescr,mailfield)
{
	/*params:
	setup array of required fields in reverse order so first which appears in document gets focus
	setup array of required fields - description for error msg 
	optional: if mailfield is given, also check mail address */
	
	//init invalidfields (description) +lastfield var
	var invalidfields,lastfield;
	invalidfields='';
	
	if(mailfield && validatemail(String(document.getElementsByName(mailfield).item(0).value))==false)
	{
		invalidfields='Contactpersoon e-mail<br />'+invalidfields;
		lastfield='email';
		
	}
	
	//validate required fields
	for(i=0; i<arrreqfields.length; i++)
	{	
		if((trim(String(document.getElementsByName(arrreqfields[i]).item(0).value)))== '')
		{
			invalidfields=(arrreqfieldsdescr[i]+'<br />')+invalidfields;
			lastfield=arrreqfields[i];
		}
	}
	

	//send all error invalidfieldss if checks failed
	//send true if checks did not fail
	if(invalidfields!='')
	{
		document.getElementById('errormsg').innerHTML=('<b>De volgende velden zijn leeg of ongeldig:</b><br />'+invalidfields);
		document.getElementsByName(lastfield).item(0).focus();
		return false;
	}
	else
	{
		return true;
	}
}