function changeImage(id, image){
	document.getElementById(id).src=image;
}




/**************************** FORM VALIDATION FUNCTIONS *************************/

function validateContact(){
	
	if(!validate())
		return false;
	
	if(!validateEmailAddress("email_address"))
		return false;
	
	return true;

}

//check that all fields with classname 'required' are filled in
function validate(formname){
	if(!formname) formname="theform";
var elems=document.getElementsByTagName('input'); 
valid=true;
for(var i=0;i<elems.length;i++){
	if(elems[i].className=='required'){
		switch(elems[i].type) {
			case "text" :
			case "password" :
				if(elems[i].value==""){
					valid=false;
					alert("Please fill in all required fields");
				}
				break;
			case "radio" :
				valid = isSelected(formname, elems[i].name);
				break;
		}
		if(!valid){
			return valid;
		}
	}
}
return true;
}

/** isChecked
 * returns true if at least one of a group of checkboxes is checked
 **/
function isChecked(formname, checkboxname){
	var isChecked = false;
	var chkbx=eval('document.'+formname+'.'+checkboxname);
	for (var i = 0; i < chkbx.length; i++) {
  	 	if (chkbx[i].checked) {
   	   	isChecked = true;
   		}
	}
	if(!isChecked)
		alert("Please tick all required checkboxes");
	return isChecked;
}

/** isSelected()
 * Returns true if one of a group of radio buttons is selected
 **/
function isSelected(formname, radioname){
	var isChecked = false;
	var chkbx=eval('document.'+formname+'.'+radioname);
	if(!chkbx.length){
		if(chkbx.checked)
			isChecked=true;
	}
	else{
		for (var i = 0; i < chkbx.length; i++) {
			if (chkbx[i].checked) {
			isChecked = true;
			}
		}
	}
	if(!isChecked)
		alert("Please tick all required Radio buttons");
	return isChecked;
}

/*** This validation function checks that an email address contains both '@' and '.' **/
function validateEmailAddress(email_address){
var email = document.getElementById(email_address).value;
	if((email.indexOf('@')==-1)||(email.indexOf('.')==-1)){
		alert("Invalid email address");
		return false;
	}
	else
		return true;
}

//Check that two fields have the same values, useful for password changes etc
function validateSame(type, retype){
if(document.getElementById(type).value == document.getElementById(retype).value)
	return true;
else{
	return false;
}
}