How to increment date in JS date library

Question

Why am I not able to increment the day by clicking on +?

  var dayLength = 1000*3600*24;
  var current = new Date();
  console.log(current);
  $('button').on('click', function(){
    var a = new Date((new Date()).valueOf() + dayLength);
    console.log(a);
   });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class="btn btn-default">+</button>

Niyoko · Accepted Answer · 2016-10-29 06:22:37Z

1

You add dayLength to new Date() which is current date. You should add it to current variable.

  var dayLength = 1000*3600*24;
  var current = new Date();
  console.log(current);

  $('button').on('click', function(){
    current = new Date(current.getTime() + dayLength);
    console.log(current);
   });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class="btn btn-default">+</button>

Note that I also change valueOf to getTime because per docs, valueOf is usually not called in user code.

answered Oct 29, 2016 at 6:22

Niyoko

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1 Comment

Behseini Over a year ago

Thanks Niyoko, this is working but can you please let me know what is the point of using window.current? why not var current?

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