在 JavaScript 中按周和月对简单的日期数组“yyyy-mm-dd”进行分组

Question

我想按周和月（在一个数组中）对一个简单的日期数组进行分组。我知道有很多例子，这个问题已经被问过很多次了，但是我找不到一个非常简单的日期格式的例子，而不是日期时间戳。

我的日期数据数组如下所示：

"timeline_data": [
  "2016-12-20",
  "2016-12-21",
  "2016-12-22",
  "2016-12-23",
  "2016-12-24",
  "2016-12-25",
  "2016-12-26",
  "2016-12-27",
  "2016-12-28",
  "2016-12-29",
  "2016-12-30",
  "2016-12-31",
  "2017-01-01",
  "2017-01-02",
  "2017-01-03",
  "2017-01-04",
  "2017-01-05",
  "2017-01-06",
  "2017-01-07",
  "2017-01-08",
  "2017-01-09",
  "2017-01-10"
]

这就是让我感动的原因：我不确定是否有一种简单的方法可以循环遍历这个数组，并将项目简单地推入新数组，或者是否必须将日期设置为修改，并用类似的东西删除“-”：

var date="2016-12-20";
var newDate = date.replace(/-/g, "");

显然，“-”必须被替换。

希望有更简单的方法。

Answer 1

我会做类似以下的事情，希望 cmets 就足够了。可能有一种更时髦的方式来解决它，但这种方式对我来说相当清楚：

/* Helper to get the ISO week number of a date
** @param {Date} date to get week of
** @returns {Array} [year, weekNumber]
*/
function getWeekNumber(d) {
  d = new Date(+d);
  d.setHours(0,0,0,0);
  d.setDate(d.getDate() + 4 - (d.getDay()||7));
  var yearStart = new Date(d.getFullYear(),0,1);
  var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7);
  return [d.getFullYear(), weekNo];
}

/* Parse ISO 8601 format date string to local date
** @param {string} s - string to parse like 2016-12-15
** @returns {Date}
*/
function parseISOLocal(s) {
  var b = s.split(/\D/);
  return new Date(b[0],b[1]-1,b[2]);
}

var data = [ "2016-12-20", "2016-12-21", "2016-12-22", "2016-12-23", "2016-12-24", "2016-12-25", "2016-12-26", "2016-12-27", "2016-12-28", "2016-12-29", "2016-12-30", "2016-12-31", "2017-01-01", "2017-01-02", "2017-01-03", "2017-01-04", "2017-01-05", "2017-01-06", "2017-01-07", "2017-01-08", "2017-01-09", "2017-01-10"];

// Prepend year and week number to dates, e.g. "201651:2016-12-20", then sort
var arr = data.map(function(s){
  var week = getWeekNumber(parseISOLocal(s));
  return week[0] + ('0' + week[1]).slice(-2) + ':' + s;
}).sort();

// Group in arrays by week in an object
var groupedObj = arr.reduce(function (result, value) {
  var b = value.split(':');
  if (!result[b[0]]) result[b[0]] = [];
  result[b[0]].push(b[1]);
  return result;
},{});

// Grab arrays in order of week number. Sort keys to maintain order
var groupedArray = Object.keys(groupedObj).sort().map(key=>groupedObj[key]);

// Final set of grouped dates
console.log(groupedArray.join('\n\n'))

getWeekNumber 函数借用自here。