js时间与毫秒互相转换

var startDate ='2018-07-09 14:13:11';
    startDate= startDate.replace(new RegExp("-","gm"),"/");
    var startDateM = (new Date(startDate)).getTime(); //得到毫秒数

var str = '2018-07-09 14:13:11';
var arr = str.split(/[- : \/]/);
var startDate = Date.parse(new Date(arr[0], arr[1]-1, arr[2], arr[3], arr[4], arr[5]));
console.log(startDate)

var endDate = (new Date("2018/072/09 14:13:11")).getTime(); //得到毫秒数  
var newDate = new Date(endDate ); //得到普通的时间了