analytics.js
function isEmpty (val) {
  if (null == val) return true;
  if ('number' == typeof val) return 0 === val;
  if (undefined !== val.length) return 0 === val.length;
  for (var key in val) if (has.call(val, key)) return false;
  return true;
}
function isEmpty (val) {
  if (null == val) return true;
  if ('number' == typeof val) return 0 === val;
  if (undefined !== val.length) return 0 === val.length;
  for (var key in val) if (has.call(val, key)) return false;
  return true;
}
function isEmpty ( val ) { if ( null == val ) return true ; if ( 'number' == typeof val ) return 0 === val ; if ( undefined !== val . length ) return 0 === val . length ; for ( var key in val ) if ( has . call ( val , key ) ) return false ; return true ; }
Test whether a value is "empty".

@param {Mixed} val
@return {Boolean}
Test whether a value is empty .