function validation(){

  //Set variables

  var alertString="";
  var numericExpression = /^[0-9]+$/;
  var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;

  if (document.getElementById('contact_fullname')) {  
  
        var companyName=document.getElementById('contact_fullname').value;
      
        if(!(companyName) || companyName.length==0){
            alertString+="The value for Full Name is not valid\n";
        }    
  
  }
  
  if (document.getElementById('contact_email')) {  
        
        var email=document.getElementById('contact_email').value;
        
        if(!(email.match(emailExp))){  
            alertString+="The value for Email Address is not valid (example - something@something.com)\n";
        }    
  
  }  
  
  if (document.getElementById('contact_phone')) {  
  
        var telephone=document.getElementById('contact_phone').value;
      
        if(!(telephone.match(numericExpression))){
            alertString+="The value for Phone Number is not valid (numbers only)\n";
        }    
  
  }  
  
  if (document.getElementById('contact_address')) {
    
        var address_1 =document.getElementById('contact_address').value;    

        if(!(address_1) || address_1.length==0){
            alertString+="The value for Address  is not valid\n";
        }
    
  }
    
  if (document.getElementById('contact_postcode')) {
    
        var postcode =document.getElementById('contact_postcode').value;    

        if(!(postcode) || postcode.length==0){
            alertString+="The value for Postcode is not valid\n";
        }
    
  }

  if (document.getElementById('samples_needed')) {
    
        var title =document.getElementById('samples_needed').value;    

        if(!(title) || title.length==0){
            alertString+="The value for Samples Required is not valid\n";
        }
    
  }

  
  //Check there are no errors
  if(alertString.length>0){
      alert(alertString);
      return false;
  } else return true;  
  
}