如何显示以前的日期，直到今天和聚合物的几年的下一个日期

Question

How to show previous dates till today and next dates for some years on polymer?
I tried the below script but it was not working.
I am getting only yesterday's and tomorrow's dates on console on repeat. I want the day before then the one before and so on. Also I must not go behind my present day.

<header>
  <iron-icon class="icon" icon="chevron-left" on-tap="previousDay" suffix></iron-icon>
  <iron-icon class="icon" icon="chevron-right" on-tap="nextDay" suffix></iron-icon>
</header>
<br/><br/>       



nextDay: function() {
  var currentDay = new Date(); 
  currentDay.setDate(currentDay.getDate() + 1);
  console.log(currentDay);
},

previousDay: function () {
  var currentDay = new Date();
  currentDay.setDate(currentDay.getDate() - 1);
  console.log(currentDay);
},

Answer 1

A possible solution would be:

nextDays: function() {
    var currentDay = new Date();
    var nextDays = [];

    for (var i = 1; i <= 30; i++) {
        var newDate = new Date();
        newDate.setDate(currentDay.getDate() + i);
        nextDays.push(newDate);
    }

    // nextDays will contain the 30 next days
}

previousDays: function() {
    var currentDay = new Date();
    var previousDays = [];

    for (var i = 1; i <= 30; i++) {
        var newDate = new Date();
        newDate.setDate(currentDay.getDate() - i);
        previousDays.push(newDate);
    }

    // previousDays will contain the 30 last days
}

You can simply change the number of days you want (30 in this example) and do what you want with the arrays nextDays and previousDays .

What you can add is for example cache these days so that you don't have to generate them everytime (especially if its for the same day).

Answer 2

Here is a simple solution using private variables.

 var date = (() => { var currentDay = new Date(); function previousDay() { currentDay.setDate(currentDay.getDate() - 1); return currentDay; } function nextDay() { currentDay.setDate(currentDay.getDate() + 1); return currentDay; } return { previousDay, nextDay }; })(); 

 <button onclick="console.log(date.previousDay())">Previous day</button> <button onclick="console.log(date.nextDay())">Next day</button> 

---

You can even shorten it, both can use the same function:

 var date = (() => { var currentDay = new Date(), previousDay = () => goToDay(-1), nextDay = () => goToDay(1); function goToDay(n) { currentDay.setDate(currentDay.getDate() + n); return currentDay; } return { previousDay, nextDay }; })(); 

 <button onclick="console.log(date.previousDay())">Previous day</button> <button onclick="console.log(date.nextDay())">Next day</button>