function checkForm( form, requiredFields, errorContainer ) {

  var errorMessage = "Please fill in the following fields before submitting the form: ";
  var errorFields = [];
  for ( var i = 0; i < requiredFields.length; i++ ) {

    field = requiredFields[i];

    if ( field.name == "email" && form[field.name].value.match(/.+@.+\..+/) === null ) {
      errorFields.push( field.description );
      form[field.name].style.backgroundColor='#6390C9';
    }
    else if ( form[field.name].value === "" ) {
      errorFields.push( field.description );
      form[field.name].style.backgroundColor='#6390C9';
    } else {
      form[field.name].style.backgroundColor='';
      }
  }

  if ( errorFields.length ) {
    errorContainer.innerHTML = "";
    errorContainer.appendChild( document.createTextNode( errorMessage + errorFields.join(", ") ) );
    alert( errorContainer.innerHTML );
    return false;
  }

  return true;

}