function validate_string(sourceId, targetId, imageId, image_ok, image_error, errorMessage, styleNormal, styleError, required) {

var source = document.getElementById(sourceId);
var target = document.getElementById(targetId);
var image = document.getElementById(imageId);
var text = trim(source.value);

//source.value = text;

 var valid = (text.length != 0);
 
 setMessage(text, target, image, image_ok, image_error, errorMessage, valid, required, styleNormal, styleError);
 
}

function setMessage(text, target, image, image_ok, image_error, errorMessage, valid, required, styleNormal, styleError){
  if(valid){
  target.innerHTML="ok";
  target.className=styleNormal;
  image.src = image_ok;
  return;
  }
  
  if(text.length==0){
  if(required=='false'){
  target.innerHTML="optional";
  target.className=styleNormal;
  image.src = image_ok;
  return;
  }
  }
 
  target.innerHTML=errorMessage;
  if(required=='false'){
  target.innerHTML +=" (optional)";
  }
  target.className=styleError;
  image.src = image_error;
  
  
 
}

function validate_phone(sourceId, targetId, imageId, image_ok, image_error, errorMessage, styleNormal, styleError, required) {

var source = document.getElementById(sourceId);
var target = document.getElementById(targetId);
var image = document.getElementById(imageId);
var text = trim(source.value);

//source.value = text;
var validChars = "0123456789 ";
var n = 0;
var valid = true;
for(var i=0; i<text.length; i++){
    var c = text.charAt(i);
    if (validChars.indexOf(c) == -1)
		{
		valid = false;
		}
    else{
    if(c != ' '){
    n++;
    }
    }
}
   
   if(n!=11){
   valid = false;
   }

setMessage(text, target, image, image_ok, image_error, errorMessage, valid, required, styleNormal, styleError);
 
}

function validate_email(sourceId, targetId, imageId, image_ok, image_error, errorMessage, styleNormal, styleError, required) {

var source = document.getElementById(sourceId);
var target = document.getElementById(targetId);
var image = document.getElementById(imageId);
var text = trim(source.value);

//source.value = text;

var valid = (text.indexOf(".") > 2) && (text.indexOf("@") > 0 && text.indexOf(" ") < 0);

setMessage(text, target, image, image_ok, image_error, errorMessage, valid, required, styleNormal, styleError);
 
}


function validate_postcode(sourceId, targetId, imageId, image_ok, image_error, errorMessage, styleNormal, styleError, required) {

var source = document.getElementById(sourceId);
var target = document.getElementById(targetId);
var image = document.getElementById(imageId);
var text = trim(source.value);

//source.value = text;

var valid = checkPostCode (text);

setMessage(text, target, image, image_ok, image_error, errorMessage, valid, required, styleNormal, styleError);
 
}

function checkPostCode (toCheck) {

  // Permitted letters depend upon their position in the postcode.
  var alpha1 = "[abcdefghijklmnoprstuwyz]";                       // Character 1
  var alpha2 = "[abcdefghklmnopqrstuvwxy]";                       // Character 2
  var alpha3 = "[abcdefghjkstuw]";                                // Character 3
  var alpha4 = "[abehmnprvwxy]";                                  // Character 4
  var alpha5 = "[abdefghjlnpqrstuwxyz]";                          // Character 5
  

  // Array holds the regular expressions for the valid postcodes
  var pcexp = new Array ();

  // Expression for postcodes: AN NAA, ANN NAA, AAN NAA, and AANN NAA
  pcexp.push (new RegExp ("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1,2})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));
  
  // Expression for postcodes: ANA NAA
  pcexp.push (new RegExp ("^(" + alpha1 + "{1}[0-9]{1}" + alpha3 + "{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));

  // Expression for postcodes: AANA  NAA
  pcexp.push (new RegExp ("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1}" + alpha4 +"{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));
  
  // Exception for the special postcode GIR 0AA
  pcexp.push (/^(GIR)(\s*)(0AA)$/i);
  
  // Standard BFPO numbers
  pcexp.push (/^(bfpo)(\s*)([0-9]{1,4})$/i);
  
  // c/o BFPO numbers
  pcexp.push (/^(bfpo)(\s*)(c\/o\s*[0-9]{1,3})$/i);

  // Load up the string to check
  var postCode = toCheck;

  // Assume we're not going to find a valid postcode
  var valid = false;
  
  // Check the string against the types of post codes
  for ( var i=0; i<pcexp.length; i++) {
    if (pcexp[i].test(postCode)) {
    
      // The post code is valid - split the post code into component parts
      pcexp[i].exec(postCode);
      
      // Copy it back into the original string, converting it to uppercase and
      // inserting a space between the inward and outward codes
      postCode = RegExp.$1.toUpperCase() + " " + RegExp.$3.toUpperCase();
      
      // If it is a BFPO c/o type postcode, tidy up the "c/o" part
      postCode = postCode.replace (/C\/O\s*/,"c/o ");
      
      // Load new postcode back into the form element
      valid = true;
      
      // Remember that we have found that the code is valid and break from loop
      break;
    }
  }
  
  
  return valid;
}



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