// When a user submits the tip form:
function tip_submit(){
  // Make sure "Terms of Service" is checked -- otherwise, display error box:
  tos = document.getElementById('tos');
  if (!tos.checked) {
    document.getElementById('error').style.display='';
    return false;
  }
  // Set cookie to change the current tab to "latest", then submit form:
  tips_cookie('current_tab', 'latest');
  document.getElementById('add-tip-form').submit();
}

// When a user clicks a field, remove the default string (passed) and blacken the text.
function focusDefaultValue(e, str){
   if (e.value!=str) return;
   e.value='';
   e.style.color='#000';
}

// If a form field is empty, set it back to a default string (passed) and grey out the text.
function blurDefaultValue(e, str){
  if (e.value!='') return;
  e.value=str;
  e.style.color='#999';
}

// Set a Cookie:
function tips_cookie(name,value,days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime()+(days*24*60*60*1000));
    var expires = "; expires="+date.toGMTString();
  }
  else var expires = "";
  document.cookie = name+"="+value+expires+"; path=/";
}      

// Get a Cookie:
function tip_cookie_read(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length;i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
  }
  return null;
}