js 时间戳转换成时间

function formatDate(now) { 
var year=now.getFullYear(); 
var month=now.getMonth()+1; 
var date=now.getDate(); 
var hour=now.getHours(); 
var minute=now.getMinutes(); 
var second=now.getSeconds(); 
return year+"-"+month+"-"+date+" "+hour+":"+minute+":"+second; 
} 


//1525249049950  Number


var d = new Date(1525249049950);
var c = formatDate(d);
console.log(c)