javascript - 以 YYYYMM 日期格式设置月份的最后一天 - Javascript

Question

我有一个变量，其日期值为 YYYYMM 格式。例如:

     var givenDate = "201704"

如何找出给定月份的最后一天并附加到它。例如，

     //last day of 2017 04 (April) is 30th so append value to givenDate + lastDate; 
     //that will be 20170430
      var newFullGivenDate = "20170430";

Answer 1

const date = "201704";
const year = parseInt(date.substring(0, 4));
const month= parseInt(date.substring(4, 6));
const lastDay = (new Date(year, month, 0)).getUTCDate();
const newFullGivenDate = date + lastDay;
console.log(newFullGivenDate);