JavaScript 解析日期字符串

function parseDate(str){
  if(typeof str == 'string'){
    var results = str.match(/^ *(\d{4})-(\d{1,2})-(\d{1,2}) *$/);
    if(results && results.length>3)
      return new Date(results[1],results[2] -1,results[3]);
    results = str.match(/^ *(\d{4})-(\d{1,2})-(\d{1,2}) +(\d{1,2}):(\d{1,2}):(\d{1,2}) *$/);
    if(results && results.length>6)
      return new Date(results[1],results[2] -1,results[3],results[4],results[5],results[6]);
    results = str.match(/^ *(\d{4})-(\d{1,2})-(\d{1,2}) +(\d{1,2}):(\d{1,2}):(\d{1,2})\.(\d{1,9}) *$/);
    if(results && results.length>7)
      return new Date(results[1],results[2] -1,results[3],results[4],results[5],results[6],results[7]);
  }
  return null;
}