//change background color by focus & blur event
var focusColor = '#E0F0FE';
var blurColor = '#FAFFED';

function focusTextbox(textbox) {
  textbox.style.backgroundColor = focusColor;
}
function blurRequireTextbox(textbox) {
  textbox.style.backgroundColor = '#FFFACD';
}
function blurUnrequireTextbox(textbox) {
  if( trimAll( textbox.value ) == '' )
    textbox.style.backgroundColor = '';
  else {
    textbox.style.backgroundColor = blurColor;
  }
}
function trimLeftAll(str) {
  if (str==null){return str;}
  for (var i=0; str.charAt(i)==" " || str.charAt(i)=="\n" || str.charAt(i)=="\t"; i++);
  return str.substring(i,str.length);
}
function trimRightAll(str) {
  if (str==null){return str;}
  for (var i=str.length-1; str.charAt(i)==" " || str.charAt(i)=="\n" || str.charAt(i)=="\t"; i--);
  return str.substring(0,i+1);
}
function trimAll(str) {
  return trimLeftAll(trimRightAll(str));
}