js 时间转换方法
var a = new Date();
console.log(a.toDateString() );
console.log(a.toGMTString() );
console.log(a.toISOString() );
console.log(a.toLocaleDateString() );
console.log(a.toLocaleString() );
console.log(a.toLocaleTimeString() );
console.log(a.toString() );
console.log(a.toTimeString() );
console.log(a.toUTCString() );