JavaScript 将字符串日期格式化为 yyyy-mm-dd 的方法

function formatDate(date) {
  var d = new Date(date),
    month = '' + (d.getMonth() + 1),
    day = '' + d.getDate(),
    year = d.getFullYear();

  if (month.length < 2) month = '0' + month;
  if (day.length < 2) day = '0' + day;

  return [year, month, day].join('-');
}

console.log(formatDate('Sun May 13,2016'));

2016-05-13

2014-05-11