How to find days between two dates with time in jquery/javascript

Question

I am new to jquery, how do I get the number of days between two dates with time also.

var fromDate = $("#from_txn_date").val();//2017-02-20 00:00:00
var toDate = $("#to_txn_date").val();//2017-06-20 00:00:00

my date format is yyyy-MM-dd HH:mm:ss.

How to check days? i tried but time reason i didn't get solutuion