// Clean code to avoid getElementById
function gebid(field){ return document.getElementById(field); }

// Sourced from http://www.smartwebby.com/DHTML/email_validation.asp
function checkEmail(str) {
	var at="@"
	var dot="."
	var lat=str.indexOf(at)
	var lstr=str.length
	var ldot=str.indexOf(dot)
	if (str.indexOf(at)==-1){

	   return false
	}

	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
	   return false
	}

	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
	    return false
	}

	 if (str.indexOf(at,(lat+1))!=-1){
	    return false
	 }

	 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
	    return false
	 }

	 if (str.indexOf(dot,(lat+2))==-1){
	    return false
	 }
	
	 if (str.indexOf(" ")!=-1){
	    return false
	 }

	 return true					
}

function checkForm(){
  var field = new Array("name","company","email","message");
  for (i=0; i < field.length; i++){
    // Is the length 0?
    if ((gebid(field[i]).value.length)==0){
      alert('All fields are required - a field is missing');
      return false;
    }
    // Is the email valid?
    if (field[i]=="email"){  
      if (!(checkEmail(gebid(field[i]).value))){
        alert('A valid email address is required');
        return false;
      }
    }
  }
}